I have it for more than 10 days and I love it. I also tried the previous versions and until now I always had problems with the refresh rate. With this one it is different, I cannot even realize the refresh when I read. Unfortunately, I do not have the 3G one because I would have waited for it more than three Months (apparently everybody wants it), but the Wi-Fi one works just fine.
It is incredible that I have it always in my purse and I read every time when I need to wait for something; in airport, bus, train station and others. I am using it in my office, in the evening at home. Until now I had my books, a lot of them, and with all this traveling it is not so easy to carry with me three or four books every month.
Another benefit is that I can jump from one book to another whenever I want, without the need of having them both in my purse.
With other words I have a new toy and I love it :).