Over the last few years, September was always early christmas for me because in September we would be getting the new release. And despite this being a database, their x.y.0 releases were always rock solid (with the exception of 9.2.0 and an issue with IN queries and indexes), so I'm usually upgrading very early.
This year, it looks like the releases is bit late, also caused by some on-disk storage issues for jsonb, so of course I'd like them to spend all the time they need, but I'm still very much looking forward to playing with jsonb as this will provide a nice way of solving some issues I'm having.
I'm not using the beta releases for anything bigger than quickly seeing whether clients still mostly work because updating between beta releases is a PITA due to it requiring a full restore most of the time.
The database I'd like to use jsonb with is 600GB in size and restoring a dump takes 2-6 hours depending on the machine.