Last year I made a rather short experiment trying to visit sites I like via IPv6. I also set a reminder to re-do this experiment one year later, with the same sites. If you want to find out how surfing with IPv6-Only looks like in the year 2017, just visit the post from 2016!
I'm not sure what to say about this :/
There is, at least, for Stack Overflow a posting about their (TBD) IPv6 deployment.