@mariomaestro summed it up well when he said, "The worst SMB game is still better than most of the best games out there."
It's a solid platformer that introduced some staples of the franchise, but it's just so weird! Perhaps it would have been better if the developers had tried to make it a little more like SMB1 (particularly in how Mario fought enemies) instead of just simply swapping skins from another game.
I owned all 3 SMB games growing up, and this one definitely got the least amount of playtime.
Even playing through it again last year, I just wanted to complete it so I could move on to SMB3.
I give it 3.5 stars (but rounded up to 4).