Halo 4 was a huge disappointment for me. The single player was EH. The enemies were really bland IMO. Too many bullet sponges and frustrating tactics. Not very good visual feedback for damage on the character models either. It made it very uneventful. Disliked the coridors and lack of large sections of the game.
The multiplayer had a really good feel to it. I liked the feel of the weapons and movement, but everything else was so awful. Hated the loadouts, very unHalo. Halo was always about map control and timing the spawns of weapons, that was completely removed. The dropship style weapons were annoying, unpredictable, and just not what I wanted in a multiplayer game.
Not being able to drop the flag and only being able to shoot the flagnum was stupid. I loved juggling the flag, passing it to teammates, switching to the rocket launcher to defend myself, etc.
The playlist was way too dumbed down. The removal of assault was a disappointment. The lack of any BTB objective for the first year really hurt it. I missed 1 flag CTF maps with rounds to defend and attack.
Overall the game was incredibly CODified. I'm sure plenty of people liked that. I don't. I enjoyed Halo because it was different than that game. I played Halo because I liked having a level playing field that focused more on map control and teamwork. That hardly matters anymore.