I played a couple of hours yesterday as well (going to play a bit more tonight). The gameplay itself enjoyable, but I'm concerned about the map size (the beta gives you a limited section, but I read that the full map is only around 6 sqkm) and of course with only one major story mission in the beta it's impossible to tell if the story is going to be any good.
And the side missions - while fun in the limited time I have played - all seem to essentially boil down to the same thing. Kill the bad guys. Though I guess that's not necessarily a problem when the combat itself is fun.
The Dark Zone in its current state seems like it might be next to impossible for solo players to extract loot. I don't want to complain that a multiplayer game has some content that can only be completed in groups, but most other shooters with any type of PvP multiplayer component still usually allow solo players to have fun, either through match making in game types where you can do well enough with random groups, or by making it possible for solo players to feel they accomplish something in that part of the game.
I enjoyed Destiny for a while (didn't start playing until the The Taken King expansion) - in part because the gunplay is excellent and because I enjoy shooters with RPG elements (or the reverse) - but for now I still have no real idea whether The Division is pretty much just going to end up feeling more like a one-playthrough-and-done RPG than a world where it keeps being fun to do dynamic missions and find new loot.
But if it's the former I'll probably still feel like I've gotten my money's worth if it has a decent and fairly lengthy story campaign.