Played the beta and have put ~20 hours into this (level 17).
This game epitomizes all that is wrong with the state of over hyped releases of deeply average games.
Looking at the sheer budget and time spent, this game doesn't come close to what Halo 3 offered (forget comparing the quality of gameplay) as a total package. Yeah but more paid for content later doesn't fly when this cost £50.
I don't know if Joseph Staten leaving had anything to do with it, but I'm pretty sure Activision had a hand in making this as sterile, safe and focus tested as possible.
The mechanics feel like Halo-lite made to appeal to anyone and everyone. The repetitive nature of the game is insulting to the player, made worse by fantastical promises of story and vast worlds combined with the pre-release trailers citing how many 'awards' this shit had already won.
Disgraceful practice from both developer and publisher. Would give it a 5/10, and that's being generous as a huge Bungie Halo (1-ODST) fan.
Edit. The missions where the robot scans something and I have to defend are awful. It was okay in Goldeneye in the Control mission as a one off, but here in 2014, it's awful and lackluster design.