Maybe the single most annoying thing about Ubuntu is that the Software center (the supposed library of application packages) consistently hangs. See screenshot, taken after 10 minutes of wheel-spinning.
Yes, I can unjam it via the command line, by uninstalling and reinstalling, but it's ridiculous that I have to do it in the first place.
@dangillmor I don't think Ubuntu is more user friendly than Debian anymore. For all its warts, Linux/BSD is still freedom, and freedom isn't free. Proprietary operating systems are more akin to fascism.