I didn't expect to get so much from a free app, I like the app and I think you have an opportunity to make this into the #1 wallpaper app. You just have to make couple minor changes, first off.
1) I would make a couple of interactive/Motion wallpaper. Ex: Someone juggling the ball.
2) Pictures need to be tiny bit more 3D,
3) having a ton of ads doesn't make someone what to buy the full version.