This probably should not be necessary to say but... Based on some issues that cropped up in the Xbox One version of the game it probably DOES need to be said...
You need to be sure that you save your game often - especially after getting a nice piece of Kit, completing a special or quest task, killing a major monster, and the like. Why?
Well it seems that there are some spots in the game where it can actually crash. And then there are the Updates - I was in the middle of a major mission and the game cut out and informed me that it had to be updated. It did that at the worse possible time - I had just killed a monster that was insanely difficult (it was a lot higher than I was) and, when the game resumed? Not dead.
So yeah, guys, gals, mates, please remember to save your game often. Umkay?