Finished it about an hour ago.
Really enjoyed it, there is a lot of content if you strive to do a lot of it, but if you blitz the main story you'll probably be looking at around 20 hours of gaming.
Personally the voice acting from Connor was terrible, the bugs and animations at time where amateur at best, the hunting aspect was pointless and so was the trading and assassins guild stuff.
I managed to go through the entire of the game with the weapons you get from the beginning, never upgraded, constantly countered enemies, there was no challenge from the combat.
And since when did they remove the "Assassin" from the game? Everytime i went to kill a key target it was hardly stealthy or worth of an assassin. Just felt they created a 3rd person action game as opposed to a 3rd person stealth assassin action game.
The story was interesting, but it reminded me of a B rate movie, add a lot of fluff, worlds going to end, poor plot writing, just add special effects.
The ship combat was brilliant, i really enjoyed that a lot, though once you upgraded the ship you became pretty much unstoppable.
Overall i'd put this probably 2nd to last or last in the series:
Ass 1
Ass 2
Revelations
Ass 3
In that order, ironically as the series progresses the quality seems to be diminishing.
Hopefully they'll let this series go now and let it be, not too sure they can milk much more out of the series with the damage that has been wrought by this instalment.
Again, just goes to show, you should never listen to review sites.