Having tried her out on the PBE a while ago, for like 15 mins, I can say that her Ulti not so much knocking champions away (only minimally) as that it will be great for the knockup itself. I already foresee nerfs to her though. Her glitterlance at level 4, with 15%CDR behind, has a CD of 7.5, and costs a mere 55mana (spammable like hell), it also nearly cleans a creep wave (and that is with zero AP stuff, but only Support items). Whimsy is neat, comparable to a silence, but a bit stronger, and as a speed buff it adds actually a nice increase (If you use it on yourself, you fly on her staff). Help, Pix is really something to get used to. You can pop it on an ally, and if you use your attack, the pixie, while sitting -on- your ally, will also attack the enemy you aim for, but from your allies position from, which opens quite a few tactical options.
Her autoattacks make last hitting super easy, btw.
She's a great support champion, I feel, but she'll take a hell of a lot of skill and good judgment to use properly.
Oh, and her ratios are rather good, so I have the feeling you want to build your 2x Gp5 items, then go straight for AP stuff, instead of aura items.
AP goes into the ulti as well, for example, as well as the shield she can give.