Really enjoying Jaunty!
There was only one slightly annoying issue with the graphics being slower (now fixed for me). I have since learnt that there's some very good speedups coming in the next linux kernel too - since a lot of the intel video driver has moved there now. This means it will reuse a bunch of the highly optimised memory management code and also be maintained as the kernel is maintained... meaning less problems. It also means that the driver can be optimised by very good kernel hackers, and the X and framebuffer drivers can use the same code.
My wacom tablet is now autodetected... and works with touch sensitivity without it being plugged in at the beginning. Means I don't have to remember to plug it in before I start X... and no configuration needed either.
The trackpad is working much nicer, and does not misbehave :)
There is a standard kernel, a low latency kernel... and a realtime kernel all apt-get able! The realtime kernel is really nice for sound/music/video/game apps. Better than anything available from windows/OSX.
Copy/paste in gvim seems sane :) Yes! (It has the best copy/paste of windows/OSX/linux for a programmer).
Resizing my ext3 HD was quite simple... so I regained an extra 100 gigabytes which was unused on it. It resized it live - whilst I was still using it :)
Using an extra monitor is now very nice. Better than my experiences with OSX/windows. Since I can tell Ubuntu where my monitors are in the real world... so if I have one up high and to the right - when I drag a window between the two, it looks to be in the correct position physically. Also the resolution on my external monitor is the full resolution - better than what the windows driver can do.
Python2.6 - 64bit optimized (4x faster python than something like the 32bit python2.5 that comes with the latest OSX). Lots of recent python modules all apt-get able :) One of the best - if not THE best system pythons around. If you love python, you'll love ubuntu - you can also install multiple pythons at once really easily. So I can have 2.5, 2.6, and 3.0 all installed at once, without any hassles.
A whole bunch of little things have been tweaked and polished.
Haven't had a chance to check out lots of audio stuff yet... it'll be interesting to see if they've improved that at all. Will report back on audio findings soon.
Unfortunately they broke joystick support at some point... here's the ubuntu SDL joystick bug report.