I just turned on the info display and rotated the LCD it will not rotate tall, but it does stay inline with the camera body. Thus when you flip it, the display is still right side up. (However,If you take pictures with the camera upside down, you are out of luck unless you are also upside down)
The D5000 had a feature whereby the information display on the rear monitor would "re-arrange" itself into a different, portrait-formatted, display so that the contents were readable when the camera was held in the portrait position.
Does the D5300, with the rear monitor folded against the body in its "normal" position, do that? I believe that is what was being asked, and according to the D5300 manual, the answer is "no".
>"it (info desplay) will not rotate tall, but it does stay >inline with the camera body."
What the D5000 did was not like "rotating tall" - the elements of the information display were re-arranged to fit the portrait format. I think we are all now agreed that the D5300 lacks that feature - as stated by Gerold in reply #1