It looks like the more negative reviews mostly share the same sentiment that haunts many Nintendo games, namely: the game is well made and a lot of fun but doesn't feel new or offer enough fresh ideas.
Nah, that is not it, as most AAA games does not feel new. Most games have a basic formula, and sequels try some things new but don't strafe far away from this basic formula.
That is the sentiment of most people that buy games (just look at the top NPD games), Nintendo is not cool anymore, most people want cinematic experiences and big sports titles (that is the only thing selling right now). Every time a Wii U game comes up, they have to talk about how Nintendo is loosing it and the Wii U woes, something totally unnecessary IMO when reviewing a game.
I don't like reviews since very long ago, I read some of them but I either buy it Day 1 or wait for some GAF feedback. But sometimes even GAF can hype something up and you end up not liking it.
in the words of Kamiya "Believe in yourself!!"