Bungie really went all out to make this a game that gave players everything they could ask for. It stumbled a bit in the storytelling and the weapon design, but the heart of the game is in the multiplayer, and there they provided such a wealth of game modes, preferences, customizations and settings that even the most hardcore players will have difficulty running out of new ways to play.
Do you buy Halo mostly for the multiplayer? Then Reach is everything you'd want and expect from Bungie's final contribution to the franchise – perfectly polished familiarity with exactly the right amount of fresh features and bold risk-taking. If you're counting on an epic, sweeping and satisfying campaign story, however, you might want to keep waiting for Halo 4.
If multiplayer is your thing, it's a must-have title. If you're a hardcore Halo fan looking to flesh out the story and really just want more of the same, then pick it up. If you're looking for an innovative FPS that pushes boundaries and helps define the genre, though, you may want to look elsewhere.
As a Halo game it rivals the nostalgia Combat Evolved instilled in us nearly a decade ago due to fully realized online multiplayer components and customizability; as a shooter, however, it feels almost as dated in so much there's little separating the core experience from past iterations.