No game ever lives up to its. Ever. Not WoW, not StarCraft, StarCraft 2 will not live up to the hype. Same thing happens every single time a game comes out.
I love the Halo series. I really enjoy FPS's. The Halo series fits me well since I'm a Sci-Fi/Military buff. But....yeah, I believe the reason Halo 1 was such a success was because it was a sleeper hit. No one really expected it to go anywhere. But it did really well. So Microsoft/Bungie decided to release a sequel, Halo 2. Built it up way too much, way too friggin much. It was a good game, but it wasn't the best game ever created for a console, as many people will attest too.
Now onto Halo 3. Well, I had fun the first three levels. I really get into the story of Halo. But....my game keeps locking up, freezing before things load, audio continuing through freezing so the sound is way the hell off, especially in cut scenes. So that's a massive minus to me. I'm going to have to take it back and get a new copy...just like what I had to do with Halo 2.
Overall, I get the feeling that Microsoft/Bungie kind of screwed the single player campaign to focus more on the Xbox live aspect. Which really sucks because I cannot get Xbox Live. So thank you Microsoft for screwing the people who cannont get or afford to play online, because we get to experience about 1/4 of what the game is supposed to be.
But I will say this, 4 player support on Legendary campaign while in the same room as HAC, Beast, Shadow, beta, etc., is going to kick ass. Nothing is quite as fun as tearing ass with three of your friends, especially, like HAC said, I can yell at them for screwing up.
/rant off