Good puzzle game with a creative concept, using portals to get to a goal destination. (Now we are thinking with portals >:D)
I like the effects and visual pleasantness. Also the gameplay is very creative and controls are crisp.
The platforming is quite strictly precise, jumping require near pixel perfect precision...so you might want to tone that down and give a little leeway in platforms. Also, standing on moving platforms will not move the character and cause the player to fall, not very fun.
All in all, a good puzzle game with an interesting premise.