While the classic gameplay yet lives, Half-life: Source doesn't make enough changes to be recommendable.
For those who haven't played the original game, Half-life takes place in the Black Mesa Facility. You play as Gordon Freeman, a mute scientist who is working in the Hazardous materials department. The stage is set by an experiment which goes horribly wrong, and creates a "resonance cascade", bringing in aliens from another dimension, who quickly overrun the entire facility. You survive the initial incident, and set-off on a simple task: survival. Things get more complicated as you go, but I'm not gonna say anything more here.
The basic gameplay of Half-life is that of classic run-and-gun shooters like Doom. You'll have a wide variety of weapons at your disposal such as the iconic crowbar, a shotgun, a machine gun, grenades, a crossbow, and several others. Its ultimately a satisfying collection, since all of the guns are satisfying to use, and they all have their uses against certain foes. The game has a great variety of foes for you to face as well such as alien slaves(now days known as Vortigaunts), alien grunts, headcrabs, Ichtyosaurs, barnacles, carnivorus leeches, etc. You'll also fight human enemies that want to make sure you don't get away. The human enemies in the game are actually very intelligent, they'll do stuff like run and take cover when they need to reload, use squad tactics to cover each other, and cover themselves or inconvenience you with grenades. Ultimately, the game's foes are all satisfying to deal with.
Now you know of the greatness that was Half-life. Ah- but we're talking about Half-life: SOURCE! Not the original game! HL: Source is a rip-off since it only makes minor changes to the game. First off- there are ragdolls for both your enemies and allies (Only exception being the Barnacle as far as I can tell). The game also has some great new water effects. That's all it improves! HL:Source also adds a few problems to the game.For starters, HL:Source notably seems to be missing some interface features that the original game had, such as an oxygen counter when you were underwater (I'm pretty sure the original game had that. The tutorial indicates this). The game also notably comes with all levels already unlocked. This may seem convenient, since you can see every level without having to trudge through Half-life's incredible difficulty. But there's a catch, the game doesn't use checkpoints at all. So if you die without quick-saving at any time, you get reset all the way back to where you started your play session. So if you got to level 5 from level 1 in one life, your back to level 1 when you die! To add insult to injury: HL:Source isn't compatable with Half-life's expansions, so this cuts into the value of HL:Source if you are interested in those.
If you happened to of missed the original Half-life, HL:Source could very well be a good buy. The classic gameplay is intact, so you'll undoubtedly enjoy it. But even then, you should probably buy the original game anyway since that allows you to experience the game as it was meant to be and buy the expansions as well.
Pros: The classic gameplay is still intact... Nice new water effects...
Cons: Some interface features appear to be missing. No checkpoints. Mediocre ragdolls. Not compatable with Half-life's expansions.
Recommendable for: If you missed the original Half-life, you will enjoy HL:Source, but your better off getting the original version of the game anyway.