Everything the negative reviews say is true, as are components of the positive.
To begin with everything is good, I can even live with the weird controls as you get used to them.
But after a certain point the level design seems to exist simply to punish you for getting that far.
Enemies constantly being offscreen and having to trigger them by advancing and yet not seeing them until you do is unacceptable.
You get stars for completing levels, being an indicator of how close to perfect the developers consider doing the level is.
The stats for the achievements give an indication of how far most players get, being - 20* - 28.7%, 40* - 9.3%, 60* - 2.9%.
I have got the 60 and this was from playing 11 levels, and it doesn't take that much effort redoing the earlier levels to pad your stars.
Good game, obviously well made, but bad level design punishes you in a way that would seem that it is your fault for buying and playing the game.
In a bundle - give it a try if you can get other things you want. On it's own - do not buy.