There's no exorbitant spending here, and that ad removal IAP will take you a long way toward saving time with the chest unlocks.
Interestingly, there is no way to continue a run, so once you die..die. While the low-resolution fonts still feel a little jarring compared to the 3D art, I don't know if there was a good solution for that. The music has a great feeling to it, and there's a cool aspect to where it changes smoothly with level transitions, to where you might not even notice that the track has been building into something different.
You also can backflip, but this uses up part of your super meter.
Your enemies won't just stand there waiting for you to bop them: some of them throw projectiles, will poison you, or are ghosts that will chase you down unless you get away quickly enough. It's all a fun concept on paper, but it's such a fun game to just physically play.
For the rest of us, the Sony Playstation Portable is one of the best machines of its generation when it comes to emulation.