Unfair, but very fun

Shoots you from under your thumb often
Sometimes the ship wont move if you switch fingers
Sometimes the ship jumps across the screen instantly, getting lost if you switch fingers
Sometimes the ship drifts under your finger so you have to reposition while still dodging
Often if your finger is not exactly on the middle of the ship, youll get in situations where you cant possibly move where you need to be with that finger because control is lost past the edge of the screen
Often spawns enemies on top of you instantly, killing you no matter where you are on the screen
Sometimes invincible unavoidable enemies occupy the whole screen width and crush you
Double-click menu moves away from your finger after first click so you have to chase it then double-click

No game or app will tell you youre out of memory and need to restart more than this one. As likely as not, the error will appear when you start it.

In spite of this, its very entertaining and has a great look and feel. The "evolution" mechanic keeps it interesting and rewards you for playing, win or lose.
Music mode stages feel pretty fresh and original, with special bosses at the end too.
Ultimately it turns into a non-traditional bullet hell shooter which is neat and surprising for Space Invaders! Later stages get insanely busy and intense for long periods.
Just be prepared to die very often for things you have zero control over.

DojoMojoMofo about Space Invaders Infinity Gene