Halo. Anything under that title will be amazing.
First off, the story of Reach. This will be familiar if you read "The Fall Of Reach" which I do recommend. This is a different story though. You are the main character, Noble 6, the last member of the "Noble" Spartan team. You and Carter, Noble 1, Kat, Noble 2, Jun, Noble 4, and Jorge, Noble 5. You and your team are the only ones keeping the alien Covennant from capturing Reach, a planet which is the last line of defense between them and the Earth. Be sure to play the story before hopping online with your friends.
Now for the multiplayer. This is undoubtedly one of the best multiplayers of any game with in depth customization for your spartan, to the awesome game modes. After you start playing there may be many sleepless nights in front of you.
The Spartan customization is amazing, and will allow you to acquire many unique, interesting items. You can customize with anything from helmets, to shoulder armor, to even armor effects that add to a unique experience. The game-modes consist of laid back Griffball to the more hardcore modes like slayer and infection, where you fight to stay alive.
This game is definitely worth your money, if you haven't already got it.
10 out of 10.