I found Black/White just.. adequate in length, lol. I didn't think the main story was too long nor too short to play through- at least the first time I played through, the story definitely held me, made me want to see it through. The only thing I'd complain about is the postgame, although the postgame for me has never been good enough, since GS, haha. My standards were set far too high from the very beginning xD