Borax will raise your ph without raising your alkalinity. It is less caustic than ph up so is safer to use and store. Also, in somewhat larger quantities than you would use to raise the ph a couple of points, it will help stabilize the ph. You will not have ph swings. Finally in very large quantities (30-50 ppm in a pool) it will act as an algaecide. It is the same stuff sold under the brand name Proteam Supreme.

If someone has a ph very low (off the scale below 6.8) and needs to raise the ph quickly, ph up is probably a better choice as it moves the ph more and faster than borax, because it is more caustic. Otherwise, I am unaware of any downside to using borax for simple ph adjustments.