James Kendrick on
JKOnTheRun has done some nice reviews of the Viliv S5 and S7.
He always comments on eBook reading as He uses the eReader and now the Kindle Apps, so is quiet thorough on how well it works.
Back to the original question, I'll love to get one of these, not so much for Reading books, as for having a pocket sized portable PC as a companion device.
While I like my N800, I'm quiet aware of how much of a pain it can be at times to get something working especially if you don't have a Linux or Unix Background.
Having windows means that while you may run into issues, finding a solution is comparatively easy.