Halo Reach is a slick shooter and is a lot of fun
Its odd to say that but Reach doesnt really redefine anything it is still just such a good experience. Everything the game does from its campaign, multiplayer and Firefight mode are very well done. For the most part this is a Halo game that doesnt break too far from the mold. The Campaign has great AI, the multiplayer is a blast with friends and FIrefight is as fun as ever. But all 3 of these elements really blend well together to truly give you more mileage for your money 
If you don't know by now, Reach is a prequal to the First Halo. Since it takes place before the First Halo, there are teams of spartans out fighting. You play as a new recruit for Noble Team Spartan-312. Your Character is fully customizable and that same character carrys throughout all of the game modes. Throughout the whole game you will mostly fight beside your team. Each of the Characters in the game are pretty good, like Kat, Jorge and Carter. The Story for the game is quite excellent. There aren't many plotwist but the game tells a great tale about the Fall of Reach.
The Single Player Campaign is a blast. As usual in a lot of Halo games, the AI is smart and will definetely put up a good fight and give a good challenge. Though the game has some annoyances. The main one that I could only point out is just how annoying the game will get. 3/4 of the way through the game, specifically when your in the desert the game is really not fun. It just feels annoying when they load up your path with a bunch of enemies and even when giving you a tank it just feels like a big hassle and really hurts what otherwise is a great campaign. After that the campaign does get a lot better. 
Halo's Multiplayer is truly epic. This time around they give you a lot of customizing elements mainly with your character. You can customize everything from your helmet, chest, arms, legs, your color and more. They still have your regular match variants like Rumble Pit, Team Slayer and the likes. New game modes like Invasion are a great edition to the online experience.
Firefight is fully realized in Reach. Unlike in ODST, Reach has Matchmaking for Firefight so you can find other players to play with rather than only friends. The Firefight customizing options are almost scary in Reach. Skulls like in Halo 3 can be turned on to give different effects and you can customize things like weapons, health and how many waves will arrive or how long the game will last. There are endless possiblities 
Honestly I haven't touched Forge yet so i won't harp on it too much. Even without playing Forge this is a complege game that is well worth your money. With each element of this game being so well done, this is definetely a must-have shooter for the XBOX 360.
