I had the same feelings for Mario as you (discussed above, when I posted it I imagine I was probably about 5-10 hours in).
I do think it picks up, especially from about New Donk City. From my experiences with it, it personally isn’t a 10/10 game but it has got better and better. I just completed the main story and now the post-game has opened it up more (though I’ve literally played like an hour after only).
I’m sure you’re going to, but make sure you stick with it. It does get more and more fun IMO.