Keep in mind that when framerate is 48fps 360 degree shutter is exactly same as 180 degree shutter in 24fps. (in terms of how long the film is exposed.)Peter Jackson and Andrew Lesnie decided on a 270 degree shutter angle for The Hobbit, which means it will have higher than normal levels of motion blur.
Thus with a 270 degree shuter and 48fps, lenght of motion blur is slightly lower than in a standard 24fps film.
Meaning slightly improved image quality overall. (being shot in 5K should help as well..)