Despite some flaws, it's a fantastic game.
The gameplay is as good as ever. Fun, fast, intuitive. Halo fans will feel at home. Some multiplayer addictions may be strange to some (loadouts, kill streaks...) but after a few hours of gameplay, i feel like they were always part of the series. Surprisingly, they are well implemented and balanced.
The graphics are simply amazing. Easily one of the best looking console games this generation. The environments, character models, lightning, particle effects, etc look incredible, especially considering the scale of most battles, and the fact that this game is running on 7 year old hardware. The fantastic art direction also helps.
The music is also great. While not at the same level of epicness of Halo 3, for example, most sound tracks are surprisingly good. Their unique nature remembers me of Blade Runner and, more recently, Mass Effect series. The sound design is also brilliant. Guns finally sound like guns and explosions sound dangerous.
The campaign is pretty good aswell. It's a bit short and i didn't like some minor decisions, like the short (thank god) quick time events and the lack of scarab or similar in scale battles. The level design is great and each mission has diversity enough. Some missions take you through forests, to caves and industrial environments. Also, unlike Reach, it's good to be back to an alien explorable world again. Something i didn't like was the fact there was no campaign coop matchmaking. What's the point of having the ability to play the campaign with more players, if you can't play with randoms?
Spartan Ops is fun with friends, but gets old fast. By the time of this review, 5 episodes (25 missions) already came out. Same environments are repeated over and over. I don't understand the fact that you can only play the current episode with random players online. for some reason, there is no matchmaking for previous episodes! Also the odd lag that haunted firefight and campaign coop in Halo Reach is back. Sadly, controls are simply not very responsive in Spartan Ops.
The multiplayer is amazing! Personally, it's the best in the series. Like i said above, the loadouts are balanced and the kill streaks and kill cam are not as annoying as i though they would be. The gameplay is simply perfect and the maps are well designed. There are also cons, though. There are not many maps, and some game modes disappeared. Why no big team objective?
Halo games are known for their comunity friendly features but, in my opinion, Halo 4 gave one step back in this department. There is no theatre mode for campaign and Spartan Ops. The ability to share pics and vids is there, but the menus seem confusing. Forge is also there again. It's great and got some improvements, but it pales in comparison to other powerful map editors on the market (Trials Evolution and Far Cry 3).
Overall, Halo 4 is a great game, but it has some odd minor flaws. This is the first game from 343i, though. It's clear that the team loves the series and tried to please the fans of the first trilogy. Halo 5 is on the way, and hopefully, for the best.