The warranty and limitations on where to buy your ebooks are the two main problems for me. I had a display problem after I dropped my first PRS 505 so instead of opting for a repair, I decided to buy another one. Which is a pity as the unit is in good working condition, except that it only shows half of the display.
As for book buying limitations, I finally solved my problem by asking for
"Leaping Gnome's" help in buying Sony's gift vouchers. He so kindly helped me. Now, I can order books from Sony. I would have loved to order from Amazon since their prices are cheaper especially for new released hardcovers but there is no way around that. As for the free Sony downloads, I registered my Sony using my friend's address so I can do the free downloads. Since I did buy my Sony in the US, I don't have any qualms doing it.