Halo 3
As someone that played Halo, Halo 2, and Halo Reach, I felt it was obvious that I needed to try Halo 3 and Halo 3 ODST. Since Halo 3 was released years ago, there's not much more new info I can say on the game. The single-player campaign story made no sense to me. Doing further research, the story begins where the comic book ends. I felt it would have been better to make the game Halo 3 pick up right after where the game Halo 2 concluded, not every gamer will follow the comics or novels. Speaking of the single player campaign, the transitions between missions were poorly done. It's as if someone just skipped several cutscenes and throws you into something new. Keyes's death made no sense either, she could have gone in with more support and perhaps some body armor.
The interruptions from Cortana and Gravemind were a big nuisance throughout the game. The vehicle controls are still pretty much the same as they were in Halo (and Halo Reach) which I feel are very outdated. The physics don't feel right, and it would have made sense to use controls similar to that of other Xbox driving games.
The game also takes eons to load the campaign if you decide to play another game other than Halo 3 because it flushes the cache. The Halo "ring" takes several minutes to load when it does this. If you shut off the Xbox after playing Halo 3, and return to play Halo 3 (and not another game/demo), the "ring" loads super fast. They need to work on this in the future because I recall some issues with Halo Reach, although not as frequent.
Not much more can be said about Halo 3. The only things I'd recommend for Halo 4 are faster load times, more modern physics/controls for the vehicles (perhaps a helmet view or cockpit view ala Forza), and a better single player campaign.

I started playing Halo 3: ODST and noticed many differences from Halo 3, namely that the achievements are more similar to Halo Reach which is a good thing. They are more oriented towards single player mode which makes it more fun. The VISR mode in ODST is similar to the night vision mode in Halo Reach. All in all, I'd say that while Halo 3 was ok, I felt Halo 3 ODST and Halo Reach were better.

Overall: 3/5 stars
Halo 3
As someone that played Halo, Halo 2, and Halo Reach, I felt it was obvious that I needed to try Halo 3 and Halo 3 ODST. Since Halo 3 was released years ago, there's not much more new info I can say on the game. The single-player campaign story made no sense to me. Doing further research, the story begins where the comic book ends. I felt it would have been better to make the game Halo 3 pick up right after where the game Halo 2 concluded, not every gamer will follow the comics or novels. Speaking of the single player campaign, the transitions between missions were poorly done. It's as if someone just skipped several cutscenes and throws you into something new. Keyes's death made no sense either, she could have gone in with more support and perhaps some body armor. The interruptions from Cortana and Gravemind were a big nuisance throughout the game. The vehicle controls are still pretty much the same as they were in Halo (and Halo Reach) which I feel are very outdated. The physics don't feel right, and it would have made sense to use controls similar to that of other Xbox driving games. The game also takes eons to load the campaign if you decide to play another game other than Halo 3 because it flushes the cache. The Halo "ring" takes several minutes to load when it does this. If you shut off the Xbox after playing Halo 3, and return to play Halo 3 (and not another game/demo), the "ring" loads super fast. They need to work on this in the future because I recall some issues with Halo Reach, although not as frequent. Not much more can be said about Halo 3. The only things I'd recommend for Halo 4 are faster load times, more modern physics/controls for the vehicles (perhaps a helmet view or cockpit view ala Forza), and a better single player campaign. I started playing Halo 3: ODST and noticed many differences from Halo 3, namely that the achievements are more similar to Halo Reach which is a good thing. They are more oriented towards single player mode which makes it more fun. The VISR mode in ODST is similar to the night vision mode in Halo Reach. All in all, I'd say that while Halo 3 was ok, I felt Halo 3 ODST and Halo Reach were better. Overall: 3/5 stars