Eh, I didn't really get all the HL2 love.
Same here. This happened a lot to sequels of my favorite shooters.
I loved Half-Life, but for me HL2 was a serious letdown: It had neither the atmosphere nor the sheer size of HL. And while all this water-biking (you know what I mean) might have looked nice, it only served to break my immersion. Unreal, for example, had levels that were nothing more than tech demos, levels where you didn't do anything, but they still fit in nicely with the rest. For some reason or other, it didn't work with HL2 - even though it had Barney. Hmmm ... thinking of it, I'd rather replay Blue Shift than HL2.
While I as a Wolf3D lover was very fond of RtCW for what it was, it was way too short for my taste.
Unreal 2: Well, they cut pretty much everything that would have made me love it. Besides, it was way too short.
Doom 3 was a neat game, but it was not Doom.
Heretic 2 was so different from the first Heretic that it was interesting to play, but still, it was rather short.
Blood 2 was too different and too difficult for my taste.
There were sequels of favorite shooters I really loved, however. Hexen 2, for example, managed to keep the difficulty level and playstyle of the first Hexen while the music added greatly to the atmosphere ... and then there was Quake 4.
While Q4 was (of course) a tad too short and too linear, Q2 was so recognizable in its art style, atmosphere and story that it hurt.
Serious Sam was mindless fun, but it didn't suck me in like some other games did
. Must have been the hilariousness. That also kept me from enjoying fan-favorite NLF too much.