The bar is set!
A few minor letdowns: object conflict resolution could be better. I've been stuck between objects a time or two. Also, if you lack save space on your Xbox HD, you'll be happily exploring/concurring the Single Player campaign (thinking your progress is saving) only to find out, the next time you log in, that you're back to where you started!!! I guess this is a no brainer but a message like 'HD full, and or, Nearing full' something, anything that tells you to clean up your drive first before losing valuable game progress. This has happened to us a few times while playing. However, the game is so fricken great we haven’t seemed to mind replaying lost sequences.
One thing to note - online play is glitchy... not smooth. play the single player, build a few maps... have some fun.. but don't expect this buy to be a halo killer by any stretch.