Q1. Does this support connecting to a peer behind a NAT device?
Q2. Does this support connecting two peers each behind its own NAT?
Because a vast majority of real world cases will fall into either of these two categories.
BTW, consider that they are shipping first final version in march so NAT reversal is important. YEY!
Speaking from past experience, STUN and ICE are OK, but they got the whole process fundamentally wrong. They let the clients drive the traversal process. This is substantially inferior to letting a dedicated mediating server do that instead. I did that with one of my past projects and it helped with connecting peers in a large number of obscure scenarios.
Specifications here