I certainly use IPv6 a fair bit at home since my ISP supports it.
My modem happens to have a rather odd bug, where once in a while (every few months) it suddenly stops sending packets for IPv4, while my IPv6 packets get through fine. I don't know how it does this, since all it sees is PPPoE packets from my router, so the modem should have no clue, but somehow it does. Rebooting the modem fixes it.
The funny thing is that it takes hours for me to realize that the problem has happened, since google stuff (gmail, etc) all works fine, facebook works fine, but links to other things stop opening and I start to wonder what is going on, before finally remembering the stupid modem problem and go reboot it and suddenly gain access to the IPv4 world again. Quite a bit of the internet does work with IPv6 only these days it seems.