This game leaked a while back and there's been a few (rather useless) finds. Mugg asked me to make a topic so I figured why not.
Here is a spreadsheet I made to keep track of current finds.
So far this game feels really solid, but I'm hoping that like others games, this one will reveal some tech later on that will break it. The engine seems to behave rather similar to vanilla Superstar on GBA in that going out of bounds wants to eject you south east unlike the other 3DS M&L games. The room id's look to be similar between the two games though the test rooms seem to have been removed. I think a couple bean spots were also relocated along with a few items.
MarioWiki's page will probably be the most comprehensive one to list all the changes to this game, though a more in-depth one detailing stat changes or item changes could be something to consider.
Notably to speedruns, the two Mush Badges were moved from Little Fungitown's shop to 2 item Moles. Mush A is in a whirlpool area and AA is in Lemmy's section in Bowser's Castle. They were also considerably nerfed from what I checked, though exact calculations need to be done.
I'll keep this post updated if some new finds come up.
And no, Bowser's Minions isn't worth talking about.