Boring and crappy, but the story fixes serious problems with the end of Halo 3.
Be that as it may, this is a sequel that should've been made. The end of Halo 3 was very disappointing. Three games' worth of suffering through hordes of aliens and dealing with Lovecraftian entities, and what is the Chief's reward? To be frozen and trapped in an abyss, septillions of light years away -- literally outside of our known universe, with no hope of ever seeing Earth or his companions again.
The problem with Halo 4 is kind of the way they went about it. The appeal of Halo was in the Flood and their Lovecraftian fear-of-the-unknown appeal. Instead they swapped the Flood with a generic Saturday morning cartoon supervillain and an army of robots. That's not how sci-fi horror works, people. If they wanted to present another threat to all life in the galaxy, using some egotistical cartoonish clown to do it is NOT the way to go. They should've come up with something equally as alien, as unfamiliar, as horrifying if not more so than the Flood because that's the appeal of Halo.
The villain, some Forerunner douchebag, and his army of robots cause the game to become boring and stale -- all you do is fight them Over. And Over. And Over again. There's nothing new, nothing different from battle to battle, just the same boring-ass shit.
Even the UNSC ship and its crew aren't enough to redeem the storyline, they're all just as boring and generic. Halo 3 made a HUGE mistake killing off Avery Johnson because he was one of the only unique characters with a distinct personality; everybody in Halo 4 is a bunch of uptight military douchebags who had their personalities beaten out of them in basic training. Even the guy who pulls strings behind the (cowardly) captain's back to help you get back to Earth and warn everybody about the new Villain of the Week is very bland.
All in all it was a good try but they need writers who are more imaginative than the ones they have. And I'm sure as hell not getting Halo 5 to see how this all pans out considering it's only gonna be released on Microsoft's 1984 telescreen spy device they call the Xbox One. Ugh.
Just... read the books instead.