It's good for the leg muscles, it's good to sober you up, and according to Chinese medical lore it's good for the kidneys: however, it's really bad for giving you piles.
The fact that in most stations in Japan of a night most of them have been used by drunken salarimen with yaki-niku, too-much-beer-and-coffee-to-sober-them-up bowels (or just useless drunken gaijin with weak squat muscles) who haven't sat straight pretty much guarantees them a pass from me.