I'm not much of a online multiplayer gamer so Splatoon does nothing for me. But people love it and I'm not denying that it's Wii u's most important game.
There are some good games on Wii U, but compared to Wii, number of great games on Wii U is pathetic. Bayo 2, SM3DW, MK8, Splatoon, XCX and W101. And two of them were not made by Nintendo. Rest are all filler games. That actually proves one point: Nintendo needs to stop making crap filler games like Starfox Zero or Animal Crossing Amiibo Party and start funding more second party games. Look how Bayonetta turned out.