I thought it was interesting, iiuc the proposal is that you can design a protocol like Paxos that allows you to guarantee that some replica will win in the future, I'm not sure how useful this is in practice though, since you won't know that your (you being the client) writes are winning until after the fact, and no replica could give you the true state until convergence. I find the claim that this represents partial progress slightly misleading, but interesting nonetheless.
Flexible paxos doesn't change the underlying guarantees at all, whereas this does.