It's really interesting to see that most people respond in regards to graphics. Nvidia marketeers must be smiling.
Why should a game's up-to-dateness be based upon eye candy? Why aren't gameplay innovation and experimentation, stroytelling, input set up etc. as, if not more, important?
It's no surprise Portal got the attention it recieved. It might not have looked extra-purty, but it did something pretty novel.
In all honesty, portal, at heart, was a bog-standard puzzle game. Apart from some of the mechanics and setting, it did little to push the boundaries of the puzzle genre, and kept to the puzzle genre cliches and frameworks.
In a world where graphical fidelity over-rides gameplay, stories and so forth, all we end up with is Quake with more colours and polygons. To be facecious, but with some conviction - Crysis was little more than Quake 2-with-bells-on.
Anyway, rant over.
Half Life 2, and the espisodes, were not ground breaking.
There is nothing wrong, however, with doing something traditional again, but doing it well. HL2 took the traditional FPS of story (in case a pretty damned good one) interspersed with corridors and baddies and did it exceptionally well. It stands shoulders above the others.
In that case, no, it's not behind the times.