That's actually kinda a hard question. I have historically liked Hitman games but, by the same token, one of the things I've liked is how it handles a breach of stealth. The games have been at their most fun when you pulled off a silent assassin rank on a level but the franchise has enormous variation in how easy or reasonable such things were. Hitman 2 made this act nearly impossible it would seem for example.
The thing is, I'm not sure why they keep using the same lead character. Having played all the games, I don't feel he's a particularly good one. He is a guy who favors the ugly side of the fence who's bald, who was apparantly the result of some bizarre experiment to create a perfect killing machine. In fact, the ongoing story is always the least important part of the game it would seem and the regular twists and turns are only interesting because of the excellent gameplay scenarios it forces.
I guess the bottom line is that I like Hitman, but not really any particular interpretation of the game.