I tried to use IPv6 about 2-3 years ago. My ISP at the time was on the leading edge of IPv6 support. However, many websites did not support it, and the fallback to IPv4 caused a performance decrease. It broke a few services in ways that were obscure, difficult to diagnose, and possibly unfixable. After some weeks, I turned it off.
I tried to use IPv6 again on my new ISP this year. And... it's not supported. I'm behind IPv4 carrier NAT.