I use Ubuntu on all of my machines (netbook, desktops, servers, EC2). One thing that drives me nuts every time I have to deal with it is the print to file dialog. Why can't it just act like a normal save file dialog? I hate having to (usually) choose "other" as the path and use the normal dialog to choose a directory, then go back and type in the file name in a different text box on the main printing window.

Generally I think Ubuntu has been a great distro that has made a ton of progress.