I never considered myself the biggest of Halo fans but I have put in my fair share of days. Halo 2 was the first Xbox game I ever owned and Halo 3 was great improvement from that. That being said, Halo 4 is my favorite title of the franchise multiplayer wise. I will the leave the judgement of the story to more dedicated fans.
The game is packed with content and thats why I have been playing it non stop despite the face I also have Black Ops2 and Assassin's Creed 3. All of you're favorite game modes are back with a bit of a 343 at times. You can even play old school team slayer if the new version is too progressive for the older fan base. 343 has already added 3 game modes since release which shows they are dedicated in the way we have come to appreciate from Bungie.
The weapons are great with fantastic sound and feel for the most part and the new unlockable armors are very fun to unlock. The overall online gaming experience is a wonderful change of paste from the blandness of COD in case you want to get away from campers or kill streaks. The game is also very responsive and I have seldom died in a way I didn't understand... something that happens every match on COD. It all makes sense, assuming you aren't lagging which has only happened to me a few times but the host is quickly switched.
Forge is greatly improved and much more simple to use once you figure out where everything is. I myself just built a simple map to start so I could figure out where everything was and all the tricks. Objects can be rotated by fixed degrees if you so choose and magnets can be turned on to help you snap objects in place. It all makes up for a less than frustrating experience that I often encountered in Halo 3 forge (trying to make a wall stand up straight).
All in all this is a great game and I have no complaints but I still wont give it a 10 because it didn't necessarily blow my mind. It's still Halo, Bungie or no Bungie. Worth a buy.