Having just completed this game not 5 minutes ago all I can say is WOW! If you've got any interest in Japanese anime films from the late 80's to mid 90's like Ghost in the Shell or Patlabor and you like single player 3rd person shooters that have an actual thought provoking story to be told then pick this up.
It plays like a cross between Gears Of War and Vanquish, with Boss battles that literally fill the screen. The pacing of the story is really well done with the action being broken up with vehicle sections. The final 3rd of the game is really up there with the genres best and there's plenty of twists and turns to keep you guessing. There is a squad mechanic based on loyalty which actually plays out in the final chapter, depending on who you've kept on side or cheesed off plays a decisive role in the end.
The shooting is tight, movement is fluid. The enemies are varied and you are constantly being introduced to new types. Coupled with being able to destroy individual limbs of the enemy robots which actually effect the way they attack, makes them very satisfying to fight.
The only drawbacks are the voice recognition which is hit and miss and the multiplayer, whilst mechanically solid, is plagued by connection issues and the fact that it's a ghost town with some game types being barren. Invasion (which is a 4 player horde mode) is actually quite good and very challenging.
A really good new IP which hopefully SEGA decide to stick with. This game NEEDS a sequal!!!