Its Halo 3 but more improved, better graphics, stronger guns and more variety!
Campaign is fun, not as good as Halo 3 but what can you expect right? You know what's going to happen! So they tried their best and campaign is about 7 out of 10.
Multiplayer is awesome, I hated Halo 3 I mean it sucked cause of no sprinting, not very good guns and the perks aren't as awesome, but now, improved weapons, also perks to help you withstand such as jetpacks! Sprinting! Camouflage and even armor shields. You can customize your spartan or as an elite as well.
Graphics have improved quite a lot and for the multiplayer too and the gamespot rating for it is just perfect. Reach is an outstanding game from the Halo series. Plus, don't expect as much, just think of it as being Halo 3 with more improvement and awesomeness!