Well, IMO, if you like toys and teletubbies, X(tra) P(roblems) GUI might look fascinating. I'm so used to AmigaOS 3.x GUI that I simply hate Windows look.
I wonder if Microsoft is heading for the fashion seen in fiction movies, where computer GUIs are very toy-like, ie. you get a message with a font that is about height of a cat and one big button in the middle of the screen :-D
BTW: why ReAction was chosen as official GUI? Programmers usually prefer MUI because it is more advanced(?). Please, note that I respect ReAction authors and don't want to start flaming - just a honest question.