Destiny a shooter with MMO elements or an MMO with a lot of shooting elements? According to a recent video interview with Chris Butcher, it's the former, and seeing as he's the Engineering Lead at Bungie he probably knows what he's talking about. But there's also some more nuance to the game which Butcher explains, and while it might not fall comfortably within the MMO header it's got a lot of persistent options.
Butcher explains in the video how the game's many public areas work -- there's no UI elements to let you know that you've entered a shared space, just the sudden sight of other players alongside the announcement of dynamic events in the area. It's certainly an interesting take on shared spaces, and it's more than you might expect from a straight shooter. If you're looking forward to the game, the video embedded past the cut is well worth your time.