I liked the combo building, I liked the variety of characters, and I even got used to the plane-switching mechanic.

I didn't adjust to the difficulty curve. I didn't like that new weapons and characters - which significantly changed the way you played, to the point of being requirements for some levels - were expensive to the point of deterrence. So I got stuck, and I got bored of grinding, and now I'm done.

It's cute, it's cheap, it's fine.