Halo 2 is probably my favorite game ever. The Campaign of the game is the best in the franchise, not to mention that it also leads into Halo 3, which is almost just as amazing. The Multiplayer is very close to perfection, with the greatest maps as well as glitches that made combat even more fun than it initially was.
Within the campaign is a very well crafted story, along with a very tightly knit weapon sandbox. Every gun serves a purpose. Alongside these is THE most frustrating difficulty in any FPS ever. Legendary is already hard enough, with enemies that melt you in seconds, snipers that could one shot the you without warning, and many other factors that make the game complete torture. Factoring in the modifier skulls, you get the unofficial difficulty "LASO" (Legendary All Skulls On), where the game becomes the ultimate test of your skill and patience. Many complain about how hard the game can get in this setting, and they would be right. Neither legendary or LASO seem like they were tested by the devs before they released the game, but if they ever did, there is no way they would be half as fun as they are. Just try to play Gravemind on LASO.
On the other hand, Halo 2's multiplayer on the Original Xbox is one of the key pioneers of the modern online FPS experience. Like really, if the Original Xbox was more popular, it would not be hard to say that a lot more people would choose Halo 2 as their favorite game in the franchise. The multiplayer is fantastic, and is only enhanced by the player discovered button combos such as BXR and Double Shot, proving that the game was blessed by the same kinds of imperfections from the development process of
Super Smash Bros. Melee, only benefitting from it more due to the FPS context. Button combos add to the game way more than they detract, and it's sad that they turn some away from the amazing multiplayer. Aside from that, the modes are the same as they appear in the other Halo games, and are just as, if not more enjoyable here than any other Halo. 2 Is also where the Franchise's map design peaks, with the additions of fan favorites Zanzibar and Headlong. Personally, District is the best map in the franchise. I could be considered a genius if the knowledge I had of the map went to something useful. Overall, everything in the multiplayer is perfect.
Many games do have imperfections, and Halo 2 is no different, but I don't think any other game will have imperfections that work for a game as well as they do here.