It holds up well in gameplay because the gravity gun is still fun. But I think most of the hype was multiplied by HL2 being such a massive step up in graphics. Nobody in my friend group played Doom 3, so for us it was going straight from HL1 and CS 1.6 to HL2. Compare the 2 games side by side and HL2 literally looked futuristic, like it shouldn't even be possible with the hardware at the time. (And to be fair my graphics card burst into flames trying to push 15 fps in the canals section so maybe it wasn't).
