It's a game changer. Clearly many apps need to optimize to the screen format (Words With Friends, Instagram...) but being able to close the screen and have it be off of my mind is a massive productivity boost - more so when I open it up to get some work done. I replaced my Galaxy Tablet, which I have used for taking notes in client meetings with the Duo. I figured that, like the Galaxy, I would use Noteshelf for that. I am finding, however, that Evernote alone works great.
I wish that
1) You could close the book and NOT hang up a call,
2) That closing the book could auto-set Do-Not-Disturb
3) That the camera was better
4) That there was more battery - I will happily accept another couple of mm in thickness for more mAH and better optics for the camera.
Finally, I added the SopiGuard black leather skin and the bumper. Total game changer in terms of not having to handle the thing like a piece of glass art in a glass art gallery.