Played the open beta. Game is definitely different (at least DZ) solo vs. group, i.e. sucks solo, so much more fun grouped. Stuff like yellow mobs will push your shit in solo in the DZ, but in a group you have all sorts of flanking tactics available to you, not to mention being able to revive each other. You can cheese stuff solo, like snipering, but once you get your gear extraction becomes an issue because if people sense that you are alone you will likely get ganked.
Meanwhile, I was logged in yesterday in various groups, at one point it was me, Sarthis and two others (group of 4), and we were extracting. This one other group of 4 that had been playing rogue the whole time, and doing a decent job, made their way towards us. We had to decide whether to stay or bail, we decided to stay, and we were able to kill two of them, causing the other two to retreat. Then we revived up and completed our extraction. Fun times.
Also, another reason to group is when you open chests, everyone gets loot. We were opening chests in the sewers using our DZ keys and everyone got to pick up blues.
I've pre-ordered this game on PS4, I know many others have as well. Feel free to add me, or if you know me from Destiny already just hit me up in game on release.
PSN ID is Caduceus888