I would say that Party Chat is a big thing missing. In game chat sucks. Simple as that. Organizing a private match using in-game chat and messages is a nightmare. I've had a lot of problems doing that on TLOU on PS3. After entering a clan on KZ: SF, party looks amazing. It's much easier to get everyone in one place and decide what to do.
A message system is basic too and trophies/achievements should be there. I would say that a big issue is that PSN and Live added a lot of social features, streaming, sharing and that's simply awesome. You can stream your game to your friends with 2 button presses, or share videos on Facebook and so on. Nintendo Network looks like it's playing catch-up with XBox Live/PSN circa 2007. Sony suffered trying to put PSN at the same level than Live because MS had 5 years of advantage. Nintendo now is suffering because PSN ironed out the problems (after 7 years!) and both evolved in the same timeframe.








