Bungie, first, 4v4 is very fun and well thought out. It is an amazing game mode.
That being said, it does fail on two fronts, on either end of the fireteam size spectrum:
1) Solo queuing sucks. In fact, the further you get from a 4 man fireteam the more is sucks. There are a couple things you could do. You could add a solo queue. You had that occasionally in D1 and it was fun. You could add larger matches, as it is harder to get together larger fireteams allowing solo queuers to blend in more. You could improve communication tools, like a means of player marking locations on the map for the rest of the team to target.
2) You failed on the social aspect of Destiny by reducing fireteam sizes. As you build networks of friends, you will find yourself wanting to go in to matches with more and more people. 6v6 was great because it gave your raid team something to do together while not raiding. We are regularly findinging ourselves having to turn people away because 4 is such a limiting number.
Those are the two major failings of PvP, as designed today.
Also, while not a failing persay, there are a few other things I find myself missing from D1:
A) I miss Rumble. It was fun to solo queue, and it was fun to have a mode where I could face off against friends.
B) I also miss Rift. A fun, fast paced objective based game. This was a game mode that kept us come back to Destiny when everything else seemed a little stale.
C) Rematches are also sorely missed. InD1, odds are, u less the match was really lopsided, you would face the same team again. I’ve had a few matches where I really wanted a rematch, and that just isn’t an option any more.
D) I miss being able to pick the game mode I want to play. Like I enjoy quick play, but I’m tired of Supremacy. Right now picking a queue is deciding if I want to endure a game mode I don’t want to play in hopes of getting one I do.
Lastly, I would like some thought put into gun balance and what guns to bring back. The guns I loved were not game breaking, the DIS 42, the DIS 47, and the Righteous Seven for example. But the, guns that completely break the balance, like the MIDA, are brought back. I thought you stole our Vaults from us so you could balance the guns. Where is the balance when you bring back broken guns, and they are still broken? I’m feeling a little ripped off on that front. I was willing to give up guns I love for balance, but you never provided that balance.
Again, 4v4 is great, but it leaves some very important aspects of the game out.