Just finished it earlier, if you liked Portal, you like this, if you didn't well what did you expect.
Not quite as impressive as the first, no one really expected Portal 1 to be any more than a little puzzle game so the clever story & humour was a great surprise. But that's not to down play the 2nd one at all, just we all knew and were expecting some witty goings on and plenty of dark humour.
Took me about 6-7 hours to complete and that was as long as I wanted the story to go on, I really enjoyed it and it would have felt stupidly stretched out if it was much longer. Didn't find it too challenging which was a bit of a shame (wasn't any easier than portal one though), but only 2 or 3 puzzles stumped me for more than a few minutes and I think I spent more time looking for the next 'portal surface' to continue on than scratching my brain. The new mechanics fit in great to the gameplay and over all it feels a much more polished and complete game than the first, not only that is longer but in how it plays and feels. For example gone are those annoying energy balls which I always found slow and annoying in the first one even when you knew exactly what you were doing.
While I've not touched it yet, the coop is obviously there as well (apparently roughly the same length (depending on who you are playing with
)), but its a shame that there's no extra challenge rooms etc for those wanting more single player stuff and it would have been a nice place to add more fiendish puzzles without them getting in the way of the single player story for those who don't want them. Hopefully we get some nice mods or a decent update along the road.
People talking about it being a console port, aside from that saving message (which I never got) there is nothing to suggest it. The graphics on the pc look fantastic, it ran perfectly on my machine and from what I saw, no micro stuttering, texture/memory issues, control issues etc or anything that you would associate with a console port.
As for that stupid shop thing, yeah stupid shop is stupid...and expensive...though I guess it gives Valve fans an expensive way to support them, much like a lot of us have done with the KF skin packs & TWI. Though the content (cheeseburger operator!) and price of TWIs stuff is much more along the lines of how supporting the dev and giving the player fluff content should be done and less charging