I've been using Linux for over two years now and have faced several upgrades/installations before. But here's my experience with upgrading from Feisty to Gutsy:
Firstly, to avoid all the busy servers I downloaded the files days before the last Gutsy was complete -- although it still took many hours (approx 8 hrs!) on my high speed connection -- then I only had a couple of files to upgrade when the new version was released. In my prior Feisty upgrade the servers were totally jammed for over a week after the release (and by the messages that I'm seeing, they are jammed again this time) -- this idea of getting the upgrade early saved me from much stress.The good things about Gutsy: some things load faster (although video seems slower), Tasty Menu panel suddenly works (was installed in Feisty, but didn't work), after reinstalling Wine the menu now has submenus, and there are lots of other good things in the upgrade...
I followed the basic upgrade instructions found on the KDE (Kubuntu) site, and overall the installation went much better then my installation to Feisty.
When I first tried to upgrade to Gutsy the installer would not start because of some problematic repositories in my package manager. I disable these and the installation ran without any interruptions.
Some of the problems that I faced before finalizing the installation included:
1) changing the video driver back to nv (standard nvidia), then I tried Envy to uninstall/reinstall a newly compiled driver -- but the program couldn't uninstall it, I then accidentally discovered that the Gnome desktop had a menu for "Restricted Drivers" that allowed me to install the Nvidia driver for my specific video card -- then when I rebooted and opened my normally used KDE destop, all was working as it should.
2) I had problems getting Compiz to work (which I was using in Feisty), so I totally removed all files/packages related to Compiz and then reinstalled -- everything works fine now (although I had to adjust my configuration again).
3) I have sound (unlike my upgrade to Feisty) but Amarok complains that "Xine cannot find the drivers" when loading. So I changed the audio driver to OGG and the problem went away --- however I don't know what the effect will be for making this change and may have to troubleshoot this in the future.
4) Some small problems include: no basket icon in Kontact, the need to reinstall/compile Wine and Vmware (and the Admin portion of the Control Center cannot/will not install Wine), I would like to see a tutorial that would help with new features (such as reinstalling the Nvideo driver, VMware, etc).
Oh, there are always things that I wish had been implemented in this new version (i.e. please work on the "help system"), but all-in-all it's a good upgrade and the process of upgrading was the easiest to date. Well done to all of you who have participated ! And thank you very much !! =D>