Wrapping up the Halo trilogy, Halo 3 literally ends with a bang and is just plain fun with Forge mode and theater.
Personally, I believe Halo 3 played it safer than Halo 2 did. Much of Halo's gameplay is still the same. New additions include equipment and some new weapons and vehicles. Weapons are more balanced and the visuals have been improved. Plenty of the music are remakes of older Halo soundtracks, but also has plenty of new ones. This marks the first orchestral Halo soundtrack in the series.
Halo 3's story should be taken as an epic journey to the finish line rather than a complex story that will twist and turn and keep you wondering. The story is quite straightforward and it did little to interest me but was full of memorable moments and pure fun. I did feel compelled to play again upon completion.
There are plenty of uneven moments in difficulty when you are mowing down on very easy enemies just so that a vehicle, like the tank-like Wraith, would be dropped and crush you on Legendary. The Scarab battles are huge fun and are a blast to replay over and over again.
Multiplayer, however, is at its absolute best here. Along with Forge and Theater mode. Halo 3's lifetime was then extended. Multiplayer was easily customizable and ranks were more refined. Bungie hit the jackpot with Forge mode, which allowed you to make changes to existing maps and Sandbox from the Mythic map pack allowed you to create your own. Theater mode allowed you to share a funny moment when you played the game, or to see how exactly you were killed. All in all, Halo 3 is a satisfying experience.