As the heavy once said:
And neither is Half-Life.
If you look at it, it really is a bit overrated. At this point calling Half-Life bad is like speaking heresy about the christian church in the 1400's. You'll get your head chopped off and be cast down into the PIT OF NO RETURN. It actually follows the average Science Fiction action tropes. Parrallel universe, aliens coming to take over the earth, the experiment gone wrong, and even the military coming in to cover up the whole affair. It really is the most cliche of cliches. If Half-Life were a movie, you'd think that it stank with how many cliche's it had. In fact, in any other media, Half-Life would be frowned upon as a thing to NOT do. The saving grace of this madening cliche-fest is the fact that it was the first time we saw those cliche's in first person. It put a fresh perspective on it all, the first time we saw too many of these cliches as we would through our own eyes! It was amazing because it put a new view on old cliches, making them seem fresh.
It's really not as good as you thought it was, but it's still one of the best games out of the 90's.
I think Team Fortress is better.
Now do to me what you will