Lucky for you. Unfortunately, I and many others have.

most of them have very good reasons for not being fixed

Some of them have inane reasons for not being fixed. From https://bugzilla.gnome.org/show_bug.cgi?id=316654

Resolution: WONTFIX "I don't have any plans to support this. My view is that any screensaver theme that requires configuration is inherently broken."

or are a work in progress

In progress for five years?

and none of them are a user experience nightmare.

I wasn't talking about nightmares, just minor things that are broken. You want nightmares? Try:

2.6.28-11 causes massive data corruption on 64 bit installations https://bugs.launchpad.net/ubuntu/+source/linux/+bug/346691 (March 2009) This one is particularly bad because they went ahead and released Jaunty with this bug. Then, the fixed kernel introduced a new bug that caused FS corruption on systems with Intel disk controllers.

ehci_hcd module causes I/O errors in USB 2.0 devices https://bugs.launchpad.net/ubuntu/+source/linux/+bug/88746 (2007)

ath5k driver connection and performance issues https://bugs.launchpad.net/ubuntu/+source/linux/+bug/461419 (2009)

[karmic regression] all network apps / browsers suffer from multi-second delays by default due to IPv6 DNS lookups https://bugs.launchpad.net/ubuntu/+source/eglibc/+bug/417757

I've been hit by all of these except the first one, and I was only saved from that because I stumbled on the bug report before upgrading to Jaunty.

It is very hard to understand how to pander to such people - but Windows is, unfortunately, a good starting point....

There are lots of problems with the ux on ubuntu that makes it problematic for a lot of people.