I have used GNOME2 and KDE3, IMHO they could both suck the paint off an iron gate. I agree though that some UNIX/Linux apps are pretty decent, 'specially OpenOffice. I've used Linux on a few different platforms, and a few UNIX flavours, and I've always had to use the CLI for something. You can get away with just using GUI if you don't do much, but if you need to get an app as source, you're using the command line, particularly if you need to get libs and stuff.
I think the reason why some people may find Linux easier to get around than RISC OS is because both KDE and GNOME clone the Windows environment as studiously as Windows attempted to clone the Mac.
I don't think there's anything wrong with using the terminal, or that it should be avoided, but a beginner is going to barf at the prospect.