It all looks really good and interesting. I was excited until the developers (talking with the IGN rep), said pretty much is not a game to play Solo. You can, yes; but you would be playing as a "lonewolf," meeting the same challenges and given certain warnings before you are about to die because there wont be AI teammates to revive you or to help; and if you do, you'll need friends to come help or just join a group. Again, meant to be co-op.
When I play with friends co-op is fun, however, the game's environment, story, challenges, characters... they all become kind of unimportant because we are all mindlessly running around shooting stuff, laughing, talking, planning or else. I don't mind that if I get to also have my own solo time to kind of get the feel of the game's world and story--having the choice is what I enjoyed about Wildlands.