Improves upon the original in every aspect. However, a short cliffhanger campaign prevents it from getting a perfect 10.
Had Halo 2 not been advertised as a battle for Earth, many would not have been disappointed. The disappointment was quickly diminished for me due to the game's fantastic gameplay. Riding vehicles is more fun than it ever was. Boss battles are simple, but a fun and welcome addition. Dual wielding is fun and useful for taking out hordes of Covenant forces. Vehicle boarding is a convenient counter-measure against vehicles and allows you to quickly snag a ride. Plenty of new vehicles and weapons were added to make a wonderful weapon set. Multiplayer is also fun with excellent level design, although glitches such as the BXR combo ruins it.
Graphics are amazing for the original Xbox and is one of the best looking games for the Xbox. Sound is also excellent along with excellent music by Martin 'O Donnell that set the mood of the game.
The story was also simply amazing. An Elite is a hero, broken, due to our efforts as Master Chief during the first Halo game. Seeking redemption, he accepts a generous offer from the Prophets of Truth, Mercy and Regret to become the Arbiter. But Master Chief's story is then forced to be set closer to Arbiter's and as a result, is mostly set on Delta Halo and ends up becoming plain and uninteresting when he could have been on Earth fighting the intense Covenant invasion.
Once the action builds up, unexpected alliances are made and Master Chief finally returns to Earth, it all ends with a cliffhanger and cheesy one-liner from Master Chief, as though the entire game was just an interactive trailer for Halo 3. The game was clearly rushed by Microsoft. Bungie just needed more time. But Halo 2 is highly replayable and extremely fun.