I had always been leary of tablet PCs, they always seemed like a gimick to me. About 3 months ago I got a screaming deal on an almost new HP TC1100, I wasn't looking for a tablet, but at the price it was selling for I decided to just get it and if it sucked I was just going to use it as a spare.
At first I thought it was just okay, but as I spent more and more time on the road it has become my favortie travel PC. My previous employer had given me a Tecra M5 which was a little to big for all the traveling I did. My current company gave me a Dell D420 a few months ago, and it's awesome but I still prefer the tablet.
The versatilite is what makes it the winner, sometimes when you are jammed on an airplane getting the screen on a traditional notebook to a comfortable viewing angle is a pain, especiall if the ass in front of you reclines their seat all they way down. but not with the tablet, for viewing documents or taking notes on an airplane it's perfect. It's also easy to use on a car, train or bus. It's a snap to use if you only have a few minutes and it may need to be put away quickly. And it's small and light so it's ultra portable, but so is the D420.
There are some downsides though. The model I have get's hot, very hot, because all the componants are in the screen portion, there isn't much of a cooling solution, and I typically don't use apps that make it really crank hard, if I did I have no idea how hot it would get, but mine is a few years old so maybe the new models have taken care of this issue. There is no optical drive, it's not the end of the world, but sometimes when I am on the road it would be really nice to have one. The notepad function sort of sucks. Now they may have cleaned it up in the newer models, and it works great for taking limited notes, if you think you are going to write on it for an hour and have everything you wrote perfectly ledgible you are going to need to practice writing on the tablet, alot. If you are going to be working on it for hours upon hours all the time, don't buy a tablet, it's good as a second or third computer, but if it's going to be your primary pc it just doesn't work, it's not meant for that sort of usage and it isn't built for that sort of usage.
I love mine, I use it almost exclusively when I travel, unless I know I have a lot of work to do in the evenings, then I take the D420. I use it at home when I am just casually surfing or need to bring some documents up for reference while I am doing work. It's ultra handy and serves as great second computer.