Finished the game myself, and I agree with General Battuta's assessment. It's a great game, just wish there were more ways to complete puzzles rather than what at times seemed like going on rails.
Still, Portal 2 has that very typical, almost unexplainable Valve quality and, feeling to it, that makes me thirsty for a certain third episode of another typical Valve game. I'm relieved they're still able to make such high quality games the same way like they used to. Gives me more faith in the company, even if I have to consider the store thing (At least it's hidden away unlike TF2).
Now to play the Co-Op mode with my girlfriend, very soon. Looking forward to that.