Coming from a new developer, I wasn't quite sure about Halo 4. Once I sunk my teeth and hours into this game, however...
When Halo 4 was announced at E3 2011, I was very excited, yet very nervous. All senses of doubt were gone after playing Halo 4. The graphics are gorgeous, with beautiful music tracks. The gun sounds have been completely redone, and sound much more realistic and intense.
The campaign mode revealed much more information about the forerunners than I thought would be told, and gave possible hints towards the storyline of Halo 5. I was very pleased how things played out, and the settings were astounding.
Multiplayer is one of the biggest factors of this game, and this is where Halo 4 really shined. Perfectly balanced, with never-stale gameplay, War Games is a true success.
Overall, this game excelled on all levels. I would have never expected this from a brand new developer, who took up the honor of one of gaming's biggest franchises, and created perhaps the best Halo game yet.