Gengar78: I myself
like half life 1 & 2... But are they worth finishing? Sure... once. I am not sure why but I have trouble replaying either of the games a second time. It might be because they are very linear in the beginning. I guess I prefer games that get going right away rather than putting you on a directed path for several minutes.
(Spoiler Alert) I honestly thought the platforming at the end of HL1 helped make you feel weak and vulnerable in an unfamiliar world. In fact, I would say that's how the whole game felt; brutal and unforgiving. (although I played on hard :P)
HL2 is well worth playing though (once) because it is great as an experience and you get to do some cool stuff along the way. In fact, I would say I like both games as story-driven fps experiences rather than repayable fps games.
I tried playing HL2: Ep: 1 but I got so bored that I stopped playing and never got around to finishing it. I heard Ep: 2 is better but honestly, I'd rather play Serious Sam TFE for the forth time than more Half Life.
If you end up not liking Half Life 1 I would recommend checking out Red Faction. Overall, I think it's more fun to play and more replayable than Half Life. One thing I like about it is how quickly it gets going compared to HL. Just be careful, there are a couple of poorly implemented stealth sections you might dislike.
Half-Life: Episode 2 was much more interesting than Episode 1 but you might end up with more questions than answers by the end if it... in fact, where's that Half--Life 3 Valve? They are good games to be played once but it feels like there's a lot of "filler" gameplay in between the story progression segments.