Great addition to the Halo franchise. Sadly, the only notable good addition is the new firefight mode.
Bad: Short campaign, same-old halo stuff
I did enjoy the game, and it was nice of them to add the second disc with the "Halo 3 Multiplayer experience" but it was unnecessary, I got rid of Halo 3 for a reason. Honestly, I only bought this game because my friends from home honestly would have flown over 2000 miles to kill me. Anyway, I started the campaign and I was pleasantly surprised until I reached the end all too quickly. The story is pretty good, you follow this "silent but deadly" rookie trooper who's drop into New Mombasa was botched by the Covenant Carrier jumping into hyperspace or whatever they call it. So basically start off all alone 6 hours after the crash in a dark city with no allies in sight. So throughout the game you are stumbling around the city taking out small pockets of covenant resistance while you try and figure out what happened to the rest of your squad. The main character goes about searching for people by looking for stuff they left behind or a camera that happened to see one of his squad-mates for a brief moment and somehow that takes you into a flashback where you play as that trooper as you try and figure out what happened to him. Anyway, thats about as much of the story I can give away without revealing too many spoilers about the game.
The other part of the game, firefight was not a disappointment. It is extremely fun and can be challenging at times. If you have no friends, you will hate this mode, all the enemies have no choice but to focus on you and you will find that you end up dead a lot. However, if you are a social being and you have a few friends, this mode is much more enjoyable, and getting the achievements for a 200k score are a lot easier. Anyway firefight is set up in waves, sets and rounds. In each round there are 6 waves and in each set there are 3 rounds, the last wave of the last round in a set usually has a few nasty customers such as hunters and hammer-wielding brutes. As you progress through the game, it will automatically turn on particular skulls that will make your life a living hell such as mythic, catch, tilt, tough luck, and so on. At the end of a set you get a bonus round where you get to compete for extra lives against an endless supply of grunts for 60 seconds. These grunts are the biggest group of grenade-happy little bastards you will ever see, you will have to dodge a lot of grenades to kill enough of them to get the extra lives for achieving the minimum score, I suggest you do the same to them and throw your grenades and whatever other explosives you have at them (the extra lives will be well worth it). Depending on the map, the enemies will appear in either drop ships or through random doors placed throughout the map. The maps that are drop ship only are the easiest because its pretty easy to focus on the spot where the enemies drop out of the 2 drop ships.
Anyway, good game, short story, and I will never play the multiplayer again, but the firefight mode actually makes up for all of those mistakes pretty well. If you like to play co-op against the in-game AI, this is a good game to play.