My doctor has been using Tablet PCs for several years. They use a stylus, and have a huge 12" screen. I imagine they are very clunky to use. The screen quality is terrible. I also imagine they cost much, much more than $499.
The iPad would be perfect for my job as a training specialist, although I would definitely need Exchange support. I'm not sure if Bento could handle my database needs. I don't do anything too crazy in Access.