Overrated, but a great game nonetheless.
Gameplay/Story: You take control of Gordon Freeman, a low-level scientist in a secret government testing facility known as Black Mesa. You soon find out that you are supposed to be in some room, testing unstable material. All of the sudden, everything goes to hell and aliens start popping out of nowhere trying to kill you. Not the most creative story in the world, but it's still entertaining. The actual gameplay is much like every other FPS in the world. Go from level to level, blowing crap up with bigger and stronger guns. However, throw in the occasional puzzle and make the enemies powerful enough that you actually have to use strategy, and you come up with a pretty decent game. Even on the easiest difficulty, you will most likely have trouble with these guys.
Graphics: ouch... just ouch... the environments look good and the aliens look good but the people... *shudder*. The heads look like blocks and there are only about 4 different human character models throughout the game. It's pretty sad. But the environments look good!
Sound: Sound effects are really cool. When the aliens shoot lightning blasts at you, you know what they are and they make you nervous. Exactly what good sound effects should do. However, the sparcely placed vo's are mostly just the same repetitive things from very generic characters. "Lets stick together!" and "Your injured, Gordon" are pretty much the only things your gonna hear.
Value: For the age of this game, it is definitely worth the money. However, once you beat it, you probably won't be playing through this one again.
While Half Life is a good game, it certainly doesn't deserve the "Greatest FPS ever made" title.