I've been running Linux on my desktop(s) for more than 10 years now. And recently I switched to (K)Ubuntu because it mostly just works. Like many others, I lost the interest in poking at the system for the hell of it quite some time ago. Now I just use it for whatever I need to do. And *Ubuntu mostly just works for me without getting in the way much. Yet it's still broken in one major way.
Like all desktop distributions I've seen to date, *Ubuntu has a real problem. It installs by default to a single partition. Notably, home is bundled with the rest. This makes updates or distribution switching needlessly complicated.
If you don't really use Unix, the /home subtree is where all your stuff gets stored. Under /home, each user of the machine gets a directory where he can do as he pleases. It's a bit like "Documents and Settings" in Windows except it's very strictly enforced in Unix because users just cannot write outside of their home directory (theoretically it's the same in Windows except everyone is often administrator and a lot of programs have bad manners). Data is stored there as well as application settings and preferences. So it's something you'd presumably want to keep even when you switch to another distribution (or do a wipe everything style of upgrade).
Unfortunately, if you follow the default install path suggested by all the desktop distributions I've seen, you get everything on the same partition, and everything on that partition will get wiped with the new system when you upgrade. Of course you have backups (you do have backups didn't you) but there's no reason you should have to go through a backup/restore cycle when keeping /home separate is so much simpler to begin with.
Should we start filing bug reports about this ? (for all of our distros really)