This is basically me, except I'd say that Portal 2 was even better.
It's a sequel so it's not a new idea, but you can feel all the extra things that went into it. The awesome soundtrack, extra characters, and the enjoyable co-op mode.
And once you get to the end... "Well here we are again"
If a Portal 3 came out, it's the only game I think I'd 100% buy without hesitation.