It's a good game.
But here are some suggestions that will help.
1. By all means, get rid of the pop-up ads, or give an option to 'x' it.
2. Camera needs a lot of fixing. And I think the auto-camera is quite useless so might as well get rid of that too.
3. Add a 'pause' button which gives an option to return to the menu or 'retry' because I accidentally hit the button and had to fight lots of time.
4. In God's name, do add more characters. Especially Petra Ral.
5. Please create difficulty level.
6. Make sure the 'skip' button cannot touch the ground. So annoying when characters move around.