The big underlying change is that MIDI 2 is duplex, which allows for device discovery, property exchange, and profile configuration. What that buys you is an arbitrary protocol for exchanging information about what things are connected to each other on the same network of devices. It should allow for a lot of cool features, like supplanting Mackie Control and Eucon with an open (or at least trivially open) protocol. One thing I think we'll see with these is more support for microtonal or arbitrary pitch systems that MIDI currently can't realize.
Jitter compensation is built into the protocol too so it should resolve some of the timing issues with USB.
Having read through the spec and written the data structures out for it already I'm not sold that it's overly complex. The additional annoyance is that it mandates JSON parsing but that isn't a tall order these days.