No, it wasn't just decent, it was a damn good SRPG game. Did you expect a crossover between Rabbids, who communicate only in screams, and Mario characters to have a rich and nuanced story? If so, I think the problems lied with your expectations.
No, I expected the game to be interesting. Instead what we got was a bland ass soundtrack, a pitiful roster in the base game, and a structure that sets in repetiton fast. If anything, the game actually tries to be more story centric than I would have ever expected, and if you're going to do that you could at least try to make your story interesting (note: interesting does not mean pretentious, complicated, or even conventionally well written).
Again the gameplay is good - it's actually much better than any of the post Fates FE games in that regard - but the game is simply dull as shit. It does a few quirky things in the beginning that work and hours later those same things are the tricks it's still hiding up its sleeve.