well tbh i enjoyed it, it wasn't uberwow omg this is a world ending game, but it was great.
I did notice a few engine tweaks, it doens't seem as choppy, motion blur is subtle but nice, the new lighting looks very nice in dark places and the water is kinda cool too.
I like the new weapon sounds and a few of the tweaks they have done with them.
I also like the free included multiplayer map pack that you can download with a code in the box
much enjoyed doing Horde on Gridlock can setup a nice defensive position on that.
Overall i think it's a good release and i enjoyed it, looking forward to some more co-op options and i love that there are bots available to get the acheivements too, which are actually attainable this time round and not stupid things like 'must do x in ranked matches' sorta thing..