I love her too. Such great design, and yes, voice over made me run around for about an hour in a custom game just listening to her quotes. Laugh fails a bit though.
Why would you ever want to attack a creep? She can clear waves with her E, and last hitting is a "must" in meta, considering how much affect junglers have. Bla-bla-bla, a ton of reasons why its ok, as it is. Its actually a bit better than Vayne's bolts in terms of on-hit stack - it remains on the enemies if you changed the target.
I certainly won't have any knock back on Vi. She is already having problems sticking to people at times. Although its probably just me playing crappy)
Great champion. Riot has done very, very well.