What got me was the powers. Daily, encounter, ct. They are COOLDOWNS. Gone were any utility spells for mages. And enchanting required 'magic dust' you got from disenchantment things. And you were (initially) stuck on a very tight set of choices and tiers that set you on a specified career path.
And multiclassing was majorly broken.
Multiclassing has ALWAYS sucked.
But for ME, whenever someone wants to 'multiclass' I keep hearing that warning bell about players who want to be good at everything. At once. And that's just not fair for anyone who want to be a single class. Nor is it really plausible to me.
As for utility spells... Those are what the 4e Rituals were for.
Also, most of those types of spells were utterly, utterly broken. From broken pointless to broken powerful. A good school was Divination. Where it ran the gamut from players "why bother" to GMs "why bother with this adventure? A simple Scry just broke it. Again."
Rituals was WoTC's attempt to fix that. Which they admit they didn't really. Also, the Essentials line of books has brought several of them back.
As for the Powers, they make sense for certain classes. Like Wizards and Clerics. After all, they've ALWAYS had cooldowns and durations. When it came to the martial classes, the concept being able to use a power only once per 'day' blew my mind. What? I keep pulling a groin muscle or something? Wouldn't I learn NOT to swing it that way after a while? Or maybe my body would adapt??