Would you say that the Wii U won this year with the best titles? Most have high review scores such as bayonetta 2, MK 8 and smash bros. Not to mention everything they released didn't break down or was full of bugs.
Of course Wii U won. I wasn't disappointed in any exclusive release for the Wii U. Mario Kart 8 is awesome. Smash Brothers is amazing. I haven't tried Bayonetta, but I've played the demo and that was awesome, plus I've heard astounding reviews for it.
All I can mention disappointments from other consoles/platforms that outnumber Wii U's disappointments. Watch Dogs, Thief, Final Fantasy Lightning Returns, Elder Scrolls Online.
Wii U's releases were of course, few, but quality over quantity for sure - I agree with you Demon_Skeith