Yes. That, for me, is by far the best bit of the game- the characters. The way wheatley and glados go smoothly from ally to antagonist, while never changing, is absolutely fantastic. Cave johnson feels a tad extraneous to me, as does that whole extra theme.
I suppose the novelty is cool, and it's all fantastic. I just got frustrated trapped down there buggering about while the faculty was about to explode.
The ending was just what portal needed. Something absolutely ridiculous, but bloody awesome at the same time. It did annoy me the scripted nature of everything after that shoot-the-moon finale, but i suppose that's the balance of cool stuff. Even if the turrets thing was a "random" too far.
Also, Glad You're Gone < Still Alive.
Where IS the national's song anyway? The end of co-op?