Halo 2 had many high expectations as to what it should be like. After I have spent time on it, I now can say that this game is quite possibly the best game on the Xbox. The more I played the game, the more I knew that there wasn't really anything wrong with it, and after you play it, so will you.
In short, the graphics in this game are simply outstanding. Unlike Halo: Combat Evolved, the devolpers of Halo 2 made many movable objects in the environment. Anything from crates and boxes to dead bodies can be moved by grenades or simply by punching them. The texturing is great and the environments never get old (unlike the first Halo, which had you backtracking through previous levels quite often.) Character models sport more detail then before, and particle effects (like explosions and gunshots) are much more realistic.
Bungie did a great job of improving the sound quality of this game. The exciting original soundtrack is no longer bland or mechanical sounding, but is now fully orchestrated with actual people playing the score. This gives the game a much more realistic approach as far as music goes. As for the voices, every little piece of dialougue is completely redone from the first game. Most of the time, you won't hear fellow marines saying the same thing that they just said five seconds ago. There are literally thousands of newly recorded voices to further enhance the the experiance. Not to mention the fact that gunshots now sound real, and background noises accompany every level, and you have yourself a game that rises above the rest.
The gameplay in single player mode can be either easy, or challenging, depending on the players preferances. This time though, Legendary mode is hard to beat. Once again, Bungie included the option to play Co-op mode, which adds a whole new twist to the original campaign. Also, Halo 2's multiplayer is not longer limited to playing split screen or LAN, as players can now go online and build up their rank as they compete against others around the world. Multiplayer has been redone completely, and is more balanced to give everyone an equal chance. Gameplay is what the Halo series is known for, and it doesn't fall short of anyone's expectations with it's sequel.
Halo 2 will probably be one of those game where people will still be playing three years from now. The single player experiance is appealing, and gamers will want to beat it on every level of difficulty, even Legendary. Xbox Live will keep people hooked to further increase their rank as people win more games. My only complaint is that you don't really get a reward for beating the game, but there are many, many secrets to be found in the campaign mode. Some of these secrets are fun to find, and will be a great reason to go back and play it again and again.
Overall, I really don't see any outstanding problems with Halo 2. Controls work fluidly, graphics are some of the best on the Xbox, and the sound quality is great. Unless you really went out of your way to activate them, there really weren't any glitches in the game either. I can't see why people would dislike this game, because the more I think about it, the more I realize that Halo 2 is probably the best First Person Shooter on the Xbox.