I have even implemented an IPv6-Only network. It fully works, including accessing IPv4 only websites like github.com via DNS64 and NAT64 at my router.
The only practically useful thing about my IPv6 enabled network is that I can run globally routable services on my lan, without NAT port mapping. Of course, only if the client is also IPv6.
Other than this one use case, IPv6 does nothing for me.
It doesn't work from most hotels, nor from my work lan, nor many other places because most "managed" networks are IPv4 only. It works better at Cafes because they are "unmanaged" and IPv6 is enabled by the most common ISPs, like ATT and Comcast and their provided routers.
Based on this experience, I think IPv6 is less valuable than us HN audience thinks it is. Private networks, NAT, Carrier Grade NAT are good enough, and internet really doesn't care about being completely peer-to-peer.
I think the adoption rate reflects this--it's a linear growth curve over the last 25 years. It should have been exponential.
I think cost of IPv4 reflects this--it is now below the peak, and has leveled off.
As surprising as it seems, IPv4 exhaustion has not been a serious problem. Internet marches on. IPv6 is still a solution looking for a problem, and IPv4 exhaustion wasn't one of them.