I don't love their pricing but it's not brutal like others I've seen. We run 3 clusters - one of which is an old legacy cluster that was our original and despite Nutanix not supporting it officially (meaning we don't pay for support on it), their support has still been helpful with it and like the other 2 clusters, uptime/stability has been rock solid.
Prism Central has definitely gotten better with the UI since the earlier days. I still prefer Prism Element in some cases, but overall it all works pretty well.
We use HYCU for backups and while I was really skeptical about it in the beginning, it is absolutely solid in a Nutanix environment. Overall we are happy with Nutanix.