I fiddled with the PS2/Xbox era ones and they were fun if a little primitive. Reading reviews for Hitman III, which are great, and wondering if it's the gaming press that I shouldn't trust or if they're actually good. Should I bother picking up I & II before picking up III? Should I pick up III?
Edit - thanks for all the honest replies. I trust you fuckers way more than I do the gaming shills in the press.
I haven't played 3 nor do I bother to follow the gaming press so I don't know what they're saying about it, but I like 1 and 2. The missions are big and complicated and have a lot of moving parts set in interesting locations or events, and that and the game design is highly conducive to replay, by not just including a lot of ways to do the main objectives, but allowing player-created replacement objectives and a rotating developer-designed "event" objective you only get one attempt at per cycle. You have a lot of options to move around in that space, plan what you want to do, and execute it, and that freedom inside a complicated environment is what hitman games excel at.
My biggest criticism would be the super-elaborate set ways to do the main objectives. Stuff like there's a guy who's attending a test of a new automated turret gun, so you can find a picture of the guy and use it to train the gun to shoot him instead of the dummy. They're kind of funny to watch I guess, but they're often really contrived setups and you definitely have to do exactly what the designers intended to make them happen. They feel less like you're using your own creativity to solve a problem and more like you're just walking down the path the designers made for you. This is made worse by the hint system they have built in to point them out, which really leads you by the hand to do these specific kills, but on the other hand if you turn that system off, they'll often rely on specific objects in kind of random spots that you'd be pretty unlikely to find by accident, like a bunch of circuit boards in a box in a tree that was dropped there by a crashed delivery plane- sure enough you hear the guys talking about the plane, but good luck finding the box in a random tree in the forest without turning guidance back on.
But that applies specifically to the elaborate story-based ways to kill the main guys, there are lots of ways to do it through your own inventiveness too, and that's the gameplay I play hitman games for.
So, yeah, I like 1 and 2, and certainly don't regret buying them. 2 is a minor improvement on 1 but they're definitely the same core game. But just try the demo of 2. The free mission is the smallest, most boring map and acts as a tutorial for the real game, but all the mechanics are in place, you can buy a single additional mission for $15 if you're still on the fence. There's no reason to play 1 or 2 first for plot reasons, since the plot in the hitman games is not what any sane person is playing it for and it barely exists in the first place. But on the other hand they're good games in their own right and, assuming 3 is a minor improvement over 2 like 2 was to 1, and 1 and 2 are obviously cheaper, there's no huge reason not to play them either. Considering you can even play the hitman 1 missions in the second engine if you own the right pack, that's the way I'd go.