Deus Ex and System Shock 2 didn't have any multiplayer or network code in it's core, while Half-Life 2 did (even in the alpha). And since then, the player model was a grey blob standing gordon, and still is :|
I don't think it's a problem that multiplayer wasn't standard. I do consider it a "bonus" that they are releasing it now, I don't see it as "putting in what should have been there" as you seem to think. Deus Ex didn't have multiplayer until LONG after the game was released, and it is still one of the best single-player FPS…
I say it lived up to its hype. Its a great game that was very engrossing. The ending dissapointed me though. It was somewhat anticlimatic. If nothing else it has set a new benchmark for environmental interactivity in a fps, and raised the bar on realism (textures and lighting) in gameing. It will also provide a great…