Samsung Galaxy Note 4 would include a Flexible Screen.

Korean media stated that the Samsung Galaxy Note 4 will be the first smartphone to feature Samsung’s famous “Youm” flexible display. Youm gathered fame as its thin, lightweight, unbreakable & flexible ofcourse.

Samsung Galaxy Note 4 was officially said to have an 'new form factor', not defined but it may had been a clue for us to know that is was the flexible screen. The devicewill use the company’s Youm flexible display, and would be three sided. As in it would act as 3 screens on 3 different planes.
These sided screen parts would be used to display notifications, messages and would will be readable at an angle. Samsung had already demoed this kind of device last year at CES 2013. The cost of such device would matter alot, LG's G Flex was really costly just because of the curved screen which provided no special use though.

Check out the video of their prototype device :

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