Well sadly I didn't win a copy of a Sony Reader in the recent Waterstone's competition but Kim at Reading Matters has been sent a review copy and gives her first impressions as she 'uses it in anger' on a train journey. Read her post - here.
I've had a peep at one in the local branch of Waterstone's and it seems easy to use (can't vouch for getting the books onto the thing though) and has a nice and clear font/background - the middle and large text sizes suited me but the small was a bit too small for my eyes.
I look forward to reading more about it from Kim.
(There's a very positive review for it over at Trusted Reviews with useful follow up comments.)