It's not short according to the producer, Mr. Inaba: "BTW, if you didn't know @PG_Kamiya is the kind of game director who will pack as much content into the game as he can until he is satisfied. If we were to give in to all of his desires, the game we'd ship would probably be some super-long action game that no one would beat. I've been teamed up with @PG_Kamiya as his producer for a long time now, and game length is something I've never once worried about. That means both the length of a single play-through and the replayability of the game. Never worried once. Never. Actually, my job really is to be the one who says "This is too %^&* long! Cut it!""
Read more at http://www.siliconera.com/2013/04/29/platinums-inaba-says-the-wonderful-101-will-make-you-glad-to-own-wii-u/#aZeAugZhf8jvMPJl.99