Here is my first impression of the game from my first 2 hours or so: the gameplay is fluid and frenetic - tons of fun with lots of great gameplay loops. The world design and all the little details from how you get into a titan to how you can interact with the AI Grunts, etc is FANTASTIC: by far the most next-gen and most fun aspect of the game IMO. The maps are good as well; I like all of them, though only a few so far have really stood out as great maps. The weapons are all well-balanced it seems and, though more variety would be nice, I don't think it would really bolster the game in any significant way. Now onto the mediocre/not so good things:
The graphics are good, but not really next-gen to me. The levels are all well-designed, but the graphics, technically speaking, don't really serve to enhance the map design, just support it (as in they are bare-minimum for me for next-gen). And finally, the campaign multiplayer is a hit-and-miss experience. On one hand, having some "important" NPC brief you before dropping into a mission is pretty cool and some of the set-pieces are really good, but a real campaign has to be a bit more controlled for this genre. Multiplayer "arena" games are simply too unscripted to properly support a campaign-style storyline, IMO, especially seeing as how I actually got kinda lost in the storyline halfway through.
Anyways, that is a pretty quick-and-dirty "review" I guess. I played on PC and I would personally give the game a 9/10 from my experience so far.