You can't compare the gameplay, but you can surely compare the ranking systems. He's saying that Halo 3 was more of a skill-oriented ranking system which required the highest TrueSkill (like Elo) attainable as a prerequisite to the max rank, and said that it was preferrable to a progression system that Halo 4 and Reach used. I do prefer the former as well, since you actually required to be really good to reach General, whereas casual people that play enough can reach max rank without much skill required.