Just for people's reference, I've copy/pasted from another website a list of the changes from 3.5 to Pathfinder in case anyone who hasn't played Pathfinder is curious. I wouldn't dream of slamming on 3.5 since I loved it and played it for years, but I definitely adore Pathfinder more now that I have the option. Some things on the list are slightly biased against 3.5 but all in all the list is very accurate in my opinion. If anyone sees anything on the list that's incorrect or if there's anything that got missed, let me know and I'll edit.
CHANGES FROM 3.5 TO PATHFINDER:
Skills have been altered and consolidated. Instead of Hide and Move Silently, there's now just Stealth. Instead of Listen, Spot, and Search, there's simply Perception. Gather information has been absorbed into Diplomacy.
Races have all been powered up; +2 to two stats, -2 to one stat (including half-orcs!), with some different abilities for some. In 3.5 terms, they're roughly an ECL of +1 (as opposed to 0 in 3e).
No one has a favored class decided by their race now - you choose your favored class, typically the one you level at 1st level, but you don't get an XP penalty for multiclassing too high above that one - you just gain an extra skill point or hit point for leveling your favored class.
Many of the classes have been options added, often to fill out "dead levels." Barbarians gain extra "rage powers," sorcerers have bloodlines that give them granted powers, wizards have varying effects for specializing, fighters get more than just bonus feats, undead-turning is actually energy channeling and also results in an AOE heal, and so on.
Classes have some sort of awesome power at 20th level, encouraging single-classing as a valid option.
Complex combat maneuvers and defenses against them have been boiled down to two numbers: Combat Maneuver Attack bonus and Combat Maneuver Defense. All
There is no 1st-level x4-kicker: if you are a Rogue you get (8 + Int modifier) skill points per level. So a 1st level, non-human Rogue with Int 10 has exactly 8 skill points (or 9 if Rogue is her favorite class and she chooses to invest there). This thing is balanced by the fact that if you have at least one rank in a class skill you get a +3 bonus in that skill.
There are no 1/2 ranks. Spending a skill point in cross-class skills gives you exactly 1 rank (but you don't get the +3 bonus).
Permanent modification to your Intelligence score may cause you to lose or gain skill points. That is: if you wear a Headband of Intelligence +2 for more than 24 hours you gain 1 extra skill point per level.
Rebalanced XP. The amount of xp to gain levels has been re-adjusted to better mesh with the character wealth by level charts. This means that after 5th level, it requires more than 1000 * level to get the next level. There are also fast and slow xp charts now (x2/3 and x4/3 required/level)
feats at every odd level
Trip, sunder, etc. have been re-balanced into combat maneuvers that utilize a Combat Maneuver base (usually the same a BAB). When trying to trip a person, you make a Combat Maneuver Attack vs that persons Combat Maneuver Defense. This works like attack vs AC. It's a much improved system and the advanced players guide adds some additional maneuvers. CM: trip, sunder, grapple, bull rush, disarm, overrun, drag, reposition, dirty trick, steal.
Favored Class: No xp penalty for multiclassing, but a level in your favored class is worth 1 hp or 1 skill point (the APG has additional options such as +1/2 point of damage to fire spells)
0th level spells: Now are more like at-will abilities. Wizards/Clerics/Druids memorize as normal, biut casting them doesn't make the caster forget the spell. Sor has infinite 0th level slots but limited known.
item creation and spells no longer have xp costs: It's all gold now!!!
Feats like power attack are now less flexible (-1/N levels) but better value. Cleave is actually useful. There are no dead feats (toughness included) Barbarian
Rage powers - about as powerful as a feat, but used only during rage.
Keeps d12 (the only class whose bab != hd)
Damage Reduction is awarded earlier and goes up better. Bard
Bardic Knowledge isn't broken. All knowledge checks even if untrained. Add 1/2 level to trained knowledge skills
The Bard has the ability to use its check in a Perform skill in place of a check with one of other two skills. E.g.: he can use a Perform (Wind [instruments]) check as a result for any Bluff or Diplomacy check. This does not mean he has to actually play an instrument, but simply that he can use the skill bonus of another skill.
Later he gains the ability to make untrained checks in stricter skills, consider all skills as class skills and take 10 even if not normally allowed.
A Deadly Performance is the 20th level death effect Bard's apotheosis.
Better/more clear rules on types of performances that count for bardic performance. Enumerated list of perform skills.
Better performance abilities Cleric
Domain Powers are increased in power and have level-dependent effects (usually a second ability that kicks in at 6-8th)
Turning is now channeling. A 30' burst of pos/neg energy that does 1d6/odd level. Feats allow you to selectively include/exclude people. Channel feats as normal (but the feats are pretty different) Druid
All shapechange spells are more precise in what abilities you gain. No more hard decisions.
Wild Shape is awared earlier and its usages per day go up more frequently. At 20th she can wild shape at will.
Can substitute animal companion for a cleric domain (and domain spell) Air, Animal, Earth, Fire, Plant, Water, or Weather Fighter
At 4th and ever 4th level a fighter can trade out a bonus feat he has for a new one as long that old feat isn't being used as a prerequisite.
Bonus will save vs fear
Bonuses on weapon groups (5th lv +4 lvs). Stacks like ranger's favored enemy bonus
Reduce armor check penalty to shields (3rd lv +4 levels
19th level dr 5/- when armored or wielding a shield
20th super critical effects with one weapon type Monk
Is actually useful now
Gains a Ki Pool: a set of ki points that increase with level. Ki points could be expended for additional attacks or temporary bonus to AC, and later to fuel supernatural abilities such as incredible jumps, self-healing, dimension door or etherealness.
Flurry of blows, treat as two weapon fighting with no off hand and bab of monks levels instead of 3/4. Can use CM instead of attacks.
After 3rd level, use monk level instead of bab for CM.
bonus feat at 1,2,6,10,14,18 from a much smaller list than fighters (improved trip and the like)
No multiclass penalty Paladin
Channel energy (see cleric)
Can have a holy spirit that buffs weapons instead of a mount
Smite Evil much more powerful (lasts the entire fight) and hurts evil dragons and outsiders more.
Lay on hands does fixed dice/level.
Mercies. Additional effects from lay on hands (cure disease, reove curse etc)
More aura abilities (bonus to self and smaller to all allies within x feet)
Spells are Charisma-based; Wisdom is no longer a favorite ability for Paladins.
Smite Evil grants Charisma-modifier bonus to AC against the smite's target. Also, at 20th level it banishes the target if it is an evil outsider.
At 20th level Paladin heals maximum amount of damage (60) with Lay on Hands or Channel Energy.
no multiclass penalty Ranger
Gets to pick combat style feats. Two weapon track or bow track. APB adds crossbow track
Instead of animal companion, can add damage/to hit vs favored enemies to allies.
Can have a quarry, a person/thing he chases that he can track at speed and gets bonus damage/to hit. At 20th, attacking quarry can be a death effect Rogue
+1/2 Rogue level to Perception and Disable Device checks against traps.
levels 2-10 get smaller rogue abilities. 10-20 as normal
20th level death sneak attack
skill consolidation makes 8+int even more powerful
Undead and Constructs are no longer immune to sneak attack and crits. sorcerer
Actually useful now
bloodlines add more abilities than domains - including automatic spells known.
except for 1 bloodline, no familiar
d6 hd wizard
all item creation feats
instead of familiar, can have arcane bond that allows casting of spell in spellbook 1/day even if you haven't memorized it. you must be able to cast it.
Specialization is usable. You must use two slots to memorize a spell from an opposed school. Two charges from a wand etc. There is a generalist school, but the special schools abilities + extra spell make them worth it.
Encounter level -- better rules for determining CR. Each monster is worth fixed xp amount to be divided evenly among players. Allows for fine tuning. Advanced Players Guide - 6 more core classes
Alchemist - bombs, potions, dr hyde mr jekle abilities
Caviler - Mounted Kinght -- similar to paladin in devition to a concept but not always LG. Gains teamwork skills.
Summoner - Arcane caster with summon special abilities + point buy summoned/spiritual companion that is the main focus of the class
Witch - Arcane caster getting power through a familiar. Drastically different spell list than wizard (cure spells!) Has hexes (one of which acts like true resurrection)
Inquisitor - a different take on a holy fighter than paladin
Oracle - a different take on divine caster. Has dramatically different 'domain'-like abilities
Traits - Mini-feats (+1 to hit when in surprise round and the like) that are more often story hooks than abilities (in general 2 at first level)
Hero points - optional rare points that allow for astonishing effects (stave off a spell for 1 round. Not die for 1 round after reaching <0 etc)
Alternate kits for other core classes (slightly different monk abilities (drucken ki). Slightly different fighter abilities (archer kit) etc.
Teamwork feats - Great bonuses that only apply if your friends also have themWhat this means:
Item creation changes. Expect your players to actually use these feats now. You wizard will craft wands, etc. He will make items for 1/2 price. Be prepared to deal with it.
CM -- Expect people, monks especially, to opt for tripping/grappling etc since it's worth it now and much easier to calculate
Sor,Mnk,Ftr fixes. People may stick with these classes since they don't suck anymore
No multiclass penalties - Expect more MC characters. Perhaps even triple/quad classes ?
Capstone abilities -- Alternatively, no multclassing since 20th level ability is so nice for each class
Animal Sidekick alternative -- No more useless mount/animal companion if you run primarily dungeon crawls.
Shape change -- DM's life is easier
Channel Energy - This will come into play a lot more. Clerics can heal a large number of people using this ability. So can paladins. They can also burn a large number of zombies. Plan accordingly.