I am mostly in Europe (outside of the 5 included EU countries) and cannot use Prime, movies, magazines, or mp3. Even downloading apps is a bit questionable, although it has worked OK for the few free apps that I have tried.
This cuts down the usefulness of the device, except for sideloaded media and Web browsing, etc. Which would be enough for me - but I'd need a larger screen size to make WWW usage enjoyable.
Not compelling enough yet. Maybe by when I am in the USA in January?