For the first few sectors (maybe an hour of play time), it feels like it's trying to pull off a Portal-styled atmosphere and failing to do so. The mechanics are interesting, but not mindblowing, and for those first few sectors it really doesn't feel like what you hoped it would.
...but then, in sector 4, the game becomes hyper stylised, introduces compltely new and unique ideas in quick succession and ramps up the difficulty greatly. It comes into its own and it's extremely enjoyable and interesting.
Definitely worth full title price, as long as you're willing to stick with it through the initial, slightly disappointing, 'training' levels.

An epic game - difficult to the point of frustration, but rewarding enough to make it all worth while. So many throwbacks to classic/retro gaming and an enourmously welcoming finish to the entire game.

Recommended big time if you like platformers :D