I am tempted by such devices, but want to wait and see what happens with MS's tablet version of windows they're supposed to be working on.
For me a tablet with docking solution to turn it into a full laptop (i.e. the docking base has full windows and the tablet part just becomes a screen when docked).
As they I have a tablet which I love for reading etc, but also a portable laptop for business trips. Currently I just have a big laptop as I need a full sized and powered laptop as that's my main work at home machine. I hate lugging it on the road, but I don't travel enough to justify buying a 2nd, smaller laptop just for travel, and no current tablets are robust enough for me to get my work done on.
So some future windows tablet with laptop dock type of thing would be an ideal middle ground for me. Tablet I use around the house, dock I take along when traveling so I can do work on that and take it instead of my heavy Thinkpad.
For now, the iPad is the best tablet, so I'll stick with it and just lug my Thinkpad on business trips.