Eh i think its pretty sweet, clocked up 20 hours on it so far, dont play it much anymore though. If its peeves you're after, mine are:
Graphics are absymal at night compared to day time (Yeah ive tried Ultra High, makes no difference)
Water has almost no texture unless you're very close to it, water reflections are nearly non-existent
The actual story campaign is surprisingly short, I only needed to do 6 - 7 story missions and i was on the Southern District. (Took me a day though cos i was doing loads of side missions and gun-unlocking)
AI can be annoying at times, some are oblivious to your presence when you're stood right infront of them, others can see you from miles away when you're crouched in long grass and hiding behind a tree.
Overall it is pretty good, didnt hold my attention for that long though.
Upsides:
Original setting and plot, Nice big map, Replay value, love the fact that you have to make decisions that can influence the game, Buddy system is cool, Graphics are, for the most part, awesome, Lots of things to do, Guns look and sound great, the degrading thing is a cool extra, Very immersive..... blah blah blah blah