I don't get this game, TBH. It's marketed as a big MMO-ey shooter with lots of content and it's really enjoyable so far mechanics-wise but I'm already level 7 after around 4 hours of casual play. I've played a few rounds of Crucible, done a couple of story missions, some adventures and 1 public event etc.
With the changes from D1, it doesn't seem like there's much to grind for, other that for the sake of grinding, and reaching level 20 can be done fairly quickly.
I got the game and the expansion pass with my Pro and decided to keep it but I'm now considering selling the pass and getting AC: Origins on PC. I don't think I'll stick with the game for long enough to play through the expansions as I'm not really hardcore enough to be that much into clans etc.