It's more telling of how Halo 4 is another half-step. Same reviewer (Jeff Gerstmann) scored Halo 3 high way back when. That game was so ambitious and added a lot to the series. Halo 4 expands a little from Reach, adds some innovations from CoD4, and replaces horde with Spartan Ops (which does look cool). I guess the difference is a new developer and a new numbered entry meant an opportunity to do something bold with the series. What it's sounding like is a very solid, very safe, same ol' Halo Game. Reach 2.
Again, it's understandable. The studio was formed to complacently make Halo games when Bungie no longer would. Maybe now that they've proven they could re-create Bungie's quality, they'll be willing to do more with Halo 5...on Durango.