The poll answers are very binary!
I have used it (mostly during beta phase), but I don't actively use it now. For me, the thing which made it work great is my corporate email/apps/intranet is all accessible via my iPad (and iPhone), but I can't use my personal PC or MacBook. Universal Control was a way I could seamlessly use my MacBook and KB/M setup to control my iPad and do a few things on my work profile on my iPad without having to get out my work laptop.