Right now the thing I'm feeling the most is the strikes. They need to focus on those and some PvP improvements for the DLC. PvP feels kind of like a diversion to me right now, rather than something I might actually focus on. They also need to jack up the rates of public events and work in improving some of the standard missions, because you run into "defend Ghost while X" way too much.
Also there are some weird basic things missing in this game. There are no audio controls whatsoever; the in-game chat is useless whenever music is playing because it doesn't shift balance when people speak. I can't hear half the shit people say, and you wind up just having to use PSN party chat to communicate. Not even having any volume sliders is a really strange omission.
Really want to get to more of these strikes though, and it makes me hopeful for the raid, as well as future strike/raid design. As long as they can continue pumping out new strikes, raids and loot I'll probably be playing this for a long while.