Played and completed this just after Xmas.
Probably one of the most entertaining FPS I've played in a good long while. About 6 hrs of campaign. Each level introduces some fun new mechanic or an inventive take on level design, then dumping it and moving on to another one. I was honestly quite surprised. Some of the ideas could span an entire game on their own.
This game also makes you feel like a complete badass. Traversal about the map is an immense amount of fun. Getting the drop on a group of grunts, whizzing about walls to escape, then drop sliding into a titan for some heavy duty craic.
You come across several titans through the story and pick up their 'loadouts' which you can switch between at will, adding variety to the big buggers to help you tackle the game. It can be a bit confusing getting used to the amount of stuff you can do with them though.
All in all this is a very accomplished game. Lots of ideas which never out stay their welcome, a story which whizzes along just nicely and looks bloody lovely. Some of the levels/set pieces are stunning.
I'm too short on time for multiplayer, but I believe it's very good. I had a few games but my skill level was too poor to put up much resistance. So I left it. I will keep hold of this game for another run through campaign though.