Best solo campaign so far in the series and addictive multiplayer makes this particular fight well worth finishing.
The biggest change since Halo 2 is of course graphics, after all Halo 3 is the first game in the series to be released on the 360. It looks very, very good. All is clean and sharp and for the most of the time performs at steady framerate. It's just what would you expect from current-gen system though Halo 3 is not any kind of eye candy. It's pretty but compared to other shooters of the time it looks only good. The same goes with physics.
The sound in Halo series has always been something extraordinary. Both music, voice overs and all the sound effects are again really great. I still think that original Halo featured the absolute best soundtrack but Halo 3's compositions stand tall on its own.
The most important thing about Halo 3 is its gameplay. Maybe it doesn't differ that much from the previous game at first but there are several key elements that improve it so much more. Level design is something I disliked in first two Halo games. This time it's not really completely different but it sure evolved, and btw Halo 3 deserves "combat evolved" in its title more than its Xbox predecessor. Superb AI, wide variety of old and new vehicles, expanded arsenal with beloved assault rifle making its way back into action or new aliens weapons, gadgets and so on Halo 3 is true pleasure to play and experience. It delivers a very, very solid portion of outstanding gameplay from start to the very end. Once again you can tell Bungie heavily borrows from Half-life series but as long as it keeps you playing it's not a bad thing.
Online multiplayer is probably one of the best in FPS games of late. It's in the same league with games like Call of Duty 4 or Battlefield: BC. For me it doesn't touch TF2 but Halo 3 focuses on a bit different type of gameplay.
It's easily the best Halo yet and a great shooter on its own. If you're looking for some awesome intense sci-fi shooting, look no further, Halo 3 is the one to play.