Ubuntu was my introduction to Linux, so I guess it was good enough to make me stick with Linux.
I like Ubuntu as a base, particularly for the PPAs and general availability of a wide variety of cutting edge software.
I don't like Canonical's development for the desktop; recent initiatives that have put me off include:
-Gwibbwer/"social desktop", (inspired by the popularity of Facebook/Twitter?)
-speeding up startup times, (inspired by the popularity of netbooks, instant-on devices, but didn't significantly speed up my system)
-Unity, (inspired by netbooks, mobile devices, but didn't function for me in 3d or 2d mode)
I feel like their roadmap is extremely whimsical
, influenced by trends rather than a philosophy. Introducing a Unity that is not release-ready, with plans to go to Gnome Shell for the next release, is a good example. I feel that in their quest to be the leader in bringing Linux desktop to the masses, they try to be too cutting edge, and end up releasing beta-quality software that gets very little maintenance before moving on to the next thing, leaving a trail of broken packages in their path. (Pulse Audio?) I think if they really adhered to their philosophy of "Linux for everybody" that they would be more focused on stability and compatibility with older hardware. Ubuntu's development path seems to me to be all about Mark Shuttleworth wanting to establish himself as a revolutionary in desktop computing.
For me, Mint takes the good parts of Ubuntu and trims the bloat, keeping and polishing the parts that make a usable desktop while ignoring the shiny and new, but broken additions. As a matter of fact, I'm really loving LMDX, and experiencing a non-Ubuntu-based distro has sparked my interest in non-Debian based systems as well. But I still won't completely abandon Ubuntu-based Mint, due to the PPAs. It's all about graphics drivers and software availability. (Sound familiar?