Yes, yes, not sure (since I don't own a 360). The Halo series is what got me into more hardcore gaming; at least, I started to play more shooting games after the impeccable first game and the second game's amazing multiplayer.
But if you're a PC gamer, you won't know (or really care) what all the buzz was about- for us, it was the fact that there was an amazing first-person shooter, made directly for home consoles, that played well without having to resort to mouse and keyboard controls.
It might be a bit hard to go back to the first game, but give it a shot- it's worth it.