I don't like it because it has a boring story, boring characters (Toads everywhere), boring enemies, boring locations, and I still don't like the battle system.
Yup, that's what somebody who wants TTYD2 would say. Jokes aside, I get where you are coming from but the locations are pretty fun! You'll be exploring a haunted hotel, a digging site, islands with parallel universes, Battle arena, etc. Not like sticker stars boring generic worlds.
Well, it has a better story than sticker star did, which sticker star had known at all.
The rest...eh, they aren't really boring, a lot of them have a lot to say. And shyguys are the main thing here, they even talk most of the time. There was this cute Shyguy sitting down with Mario on the train ride telling him it's good to relax sometimes, but when they meet again it'll be as enemies. You meet the same ShyGuy later down the road and have to battle him, once you kill him he says "Well, if I had to go I'm glad it was by you, Mario."
This game is fun, you just have to give it a try.