I'm not very good with suggestions, but you've been nice enough to help me out, so there's only two things I'll say (which aren't gonna be helpful, because this is a sketch, not the finished product.)
I personally love whole thing: she's proportioned well, has unique clothing, and has personality in her expression. One thing I might be careful of when finishing up is the sketch book. It's a little tough to tell where the top spine is going to end up (the far "right" to us.) I love the pikachu.
The middle finger on her right hand (our left) is just a little thick looking, but I'm sure you'll fix that up when you get the actual outlines in. You do hands beautifully!
Only other thing isn't really a mistake, just a personal preference. I don't like to see characters cut off at that point in the legs. Usually, I either like the whole character, or it cropped a little higher (maybe high enough to still the book?) I dunno, just anytime I cropped like that, it was because I ran out of paper. It looks good in your drawing, but if feels a little incomplete. I'd like to see if you're (I'm assuming that's you? SuperKasey!) wearing super hero boots
Take it or leave it: like I said, I'm not very good with critiques. But it looks pretty fantastic to me! :3
Oh, and I can't count, it's three things (I'm like the Monty Python Spanish Inquisition---shouldn't have watched that last night.)