Thanks! I was just interested (not planning to implement anything myself soon).

How does WebRTC perform in realistic scenarios? Is it capable to realistically compete with the big guys (Skype et al)?

Too soon to tell yet in my case, but I've been pleasantly surprised by the rapid rate of improvements, so I'd say probably yes.

Skype and Hangouts are still a little better in terms of quality and overall experience, but a standard WebRTC app is definitely "good enough", and with some tweaking, it can be great (see Appear.in).

And WebRTC brings some very important advantages over Skype, Hangouts, etc (mainly reduced friction, not having to login, better embeddability, and overall control of the experience)

I've yet to test the new VP9 codec, which should bring huge gains. And there are other tools being added to the ecosystem which will enable lots of neat use cases.