It's a fun game, nice little upgrade system and the like, but absolutely ruined by terrible controls. Not just 'oh, that's a little bit complicated', but outright unusable. I found myself unable to do anything besides occasionally flail trying to attack by nose-diving. An 'attack' function would be absolutely essential to fix this.
Ironically, that aside, it's actually a good game. There's no taking away from the rest of it, it's just really hard to enjoy when the one major problem it has is so in-the-face and detrimental to the gameplay.