I think the graphics on Halo 4 are amazing, I was blown away. A definite improvement over Halo 3, even Halo Reach.
I did find the story to be short though? As in, my partner and I have played Halo 3, ODST, Reach and now this in co-op and this was the only Halo game we completed in 2 days. Where as the others took us longer. Or maybe we just enjoyed it more so played longer, idk. We did four missions, then went to do the other four the next day and it didn't save properly so we ended up doing the 4th one over, so did five the next day.
Online is pretty good as well. Definitely an element of Call of Duty but, it's good. Love playing the Flood.
In comparison, Black Ops 2 doesn't seem to have changed/been improved where as Halo 4, wow the change was impressive! Gotta clean some litter trays, then going to shove Halo 4 in for some multiplayer