Given its influence on the genre, it probably doesn't hold up terribly well against modern standards. If you consider it in context though, it was released alongside DOOM 3, Fable, GTA: San Andreas, Star Wars: Battlefront, and Far Cry, making it much more appreciable. It's definitely worth playing if you haven't already. As for the original Half-Life, you can buy it fairly cheaply on Steam or you can play the fan-developed remake Black Mesa, which gets the gist across in a modern framework. Bear in mind, though, that Black Mesa requires that you own at least one Source game (Counter-Strike: Source, Half-Life 2, etc. Not sure if TF2 counts).