Been playing Halo 4 for several hours now and the only word I can use to describe it is fantastic. As a Halo fan I can say it's everything I hoped it would be.
I do have some advice. If you've been playing Halo for as long as I have, make sure to play it on Heroic or higher. I just finished playing though all the Halo games on Heroic and I'm so practiced up that anything less would be a walk in the park. Heroic gives enough challenge to keep it fun without the frustration that comes with Legendary.
You know what level of difficult you can handle. Don't set it too easy for yourself. Save Normal for going back to get all the terminals and other achievements/cookies. Your first play-through should be challenging and force you to use other tactics than "run out in the open and circle strafe everything in sight".
