I started looking into the JetBook not long after getting my PRS-505. Since I live in Taiwan, most of these devices aren't available locally and need to be imported. After what I paid for the Sony, I had to admit being slightly put off by the limited contrast and clarity of the screen. I don't think the JetBook will totally resolve that dissatisfaction, but the TFT screen seems to be a potential step in the right direction. I hope the next few product generations show more development in screen clarity and contrast, and not just more tagged-on functions and features. Market-driven innovation being what it is though...
Were I starting from scratch though, and knowing I'd be making my own custom PDFs the way I am for most of my books, I'd probably have gone with the JetBook rather than the Sony, even if the JetBook has the aesthetics of a 1980s boombox. I find my Sony ugly enough as it is, the JetBook takes it to a new level of potential distraction.