I think it is a great idea and that more stores should do it. If I had been given a Kindle, I'd gladly swap it

-- especially for a Sony

.
But you are right, Neil, that some people are given these devices thinking that it is something they want only to discover it is not. I think this is particularly true in the case of the Kindle because Amazon has done such a great job promoting it. People think it is easier to use and more enjoyable to use than it may be for their particular reading habits or level of technophobia.