Been using Ubuntu for a couple years, just installed the latest (Intrepid 8.10) and no big issues so far. For me, Ubuntu hits a sweet spot of usability and power. If I want to be lazy and stick with a point-and-click, GUI way of doing things I can. I keep a shortcut to a terminal on my toolbar, for those times I want to embrace my inner geek, or because sometimes, for some things, the CLI is faster or easier.
The only shortcoming of Ubuntu, in my opinion, is not really a shortcoming of the distro itself--the lack of professional-grade applications for non-computer-specific uses. This is beginning to change, but slowly.
I work on my Ubuntu partition about 80 percent of the time, but there are some things I do that are easier on the Windows side. For example, there is no tool comparable with either Snag-It or CamStudio. Sure, there are plenty of ways to do screen captures using free or Linux-compatible tools, but nothing that compares to either of those in terms of ease of use or features.
Just my $0.02.