I bought Halo 2 yesterday.
Today I finished it. Around 30 hours from purchase to finish.
There's something to be said about being sick and unable to sleep or rest properly; I've used Halo 2 to get my mind off being sick and tired and just immersed myself in the games universe. It's a good way to do it.
I liked the game, it's better than Halo, and like the first game it has a very movie-like style to the story and the way it's told, there's long video sequences between the parts, and I enjoyed them.
The artwork is improved, and there's more details. The game physics also seem better, and generally the game is much more believable. As a new thing the vehicles take clearly visible damage, there's no “health bar” for anything anymore, not even yourself, only your energy shield. There's no first-aid kits to restore health either, and it simplifies and suits the game very well.
Of course there's new weapons and enemies in Halo 2. Instead of the “sniper pistol” and not at all long-range assault rifle of Halo, there's now a proper rifle with the range and accuracy you expect from such a weapon, and a new SMG which is more like the assault rifle of old, just slightly shorter range. The rifle is fitted with a 2× scope and fire only in 3-round bursts from it's 36-round clip, and it's not possible to carry more than 3 spare clips for it. The SMG has a 60-round clip and you can carry 3 spare clips for each. Yes, you can have two SMGs at once, very lovely, but then you can't throw grenades, and reloading is very slow. You also can't holster more than one SMG, so when using two and briefly changing to the rifle and then back, you have to pick up the SMG that's dropped in the change. All of the smaller weapons can be used in tandem like the SMG, including the covenant plasma rifle.
There's a few new covenant weapons too, mostly in the big and heavy end of the spectrum, but there's also the sword that some elites use in Halo, very nice for close combat, especially since it cuts through armor very well.
The story is more complicated than the first in the series, but since they use the time needed for video sequences to explain it all, it works very well, and it's not surprising when you're suddenly a covenant elite on a special mission to kill a heretic. About 50% of the game is spent as that covenant elite.
There is one really bad thing about the story though: the final fight doesn't feel final at all, when it's over and the closing video begins it feels like this is it, the big showdown on an earth orbiting forerunner spacecraft controlled by the covenant, but with the master chief on board, get ready! But it's just the end. It feels like they had a deadline to meet or something, I felt let down when I finished the game.
Other than that, it's a fine way to waste ones time, recommended.
A small tip: don't turn subtitles off for the movie sequences, sometimes the effects to create the alien voices make it hard to understand clearly, and the subtitles are unobtrusive.