Halo 3 is the third installment of the Halo series since Halo: Combat Evolved on the original XBox, and was favorably received by critics. Halo 3 is a nicely- polished console FPS in most regards.
The developing studio of Halo 3, Bungie Studios (who, until recently, was owned by Microsoft), has admirably made continual efforts to improve each successive Halo game with moderate success, polishing graphics, pushing hardware limitations, and making some much-needed changes to gameplay - especially as it applies to the multiplayer aspect of the games.
Multiplayer is inarguably the strong suit of the Halo games, and Bungie Studios has faithfully maintained multiplayer as the strongest area of the game, with Halo 3 exhibiting the most innovative and refined multiplayer of the Halo series. The XBox Live service adds a new dimension to the multiplayer gameplay as well, providing that the players paired through the matchmaking service are tolerable opponents or teammates.
Single-player mode, on the other hand, suffers from inattentiveness to detail or refinement but is so full of plot holes and shallow, vague characters that it falls flat in its presentation. Story aside, the single-player mode can quickly becomes repetetive, being little more than endless waves of enemies with slight variance in enemy type, difficulty, and showing the occasional cutscene.
Overall, Halo 3 is worth the price (retailing for around $59.99 USD) and will probably provide hours of good entertainment.