I've had Ubuntu as my primary desktop for about a decade and the regression issue is my biggest one, especially with three monitors. Fortunately it takes me far less time to go from non-booting desktop to something usable these days, but I think that can be chalked up to practice more than improvement. That said, for the most part it continues to run smoothly, provided I wait about a month or two after each release before upgrading. Otherwise, I remain a fan - including Unity.