Here's my take. It's the 1st 3d Mario ever made. Mario 64 was a cool idea, but I hate that you could only have power ups for as long as a puzzle lasted (included all the following 3d marios), I hate HAVING to jump or spin attack all the enemies. Having fire flowers, cat suits, boomerangs, etc until you get hit is awesome, and feeling the extra pressure of not getting hit is a little invigorating. Bowser battles were the only fun part of 3d marios up until now.
The camera is increasintly improved over past entries in my opinion.
Quick note on the music; it gets way better. One of the ghost houses in particular has the best music I've heard in a Mario game maybe ever. Has some influence from luigi's mansion. Around 3 or 4 you'll get a bonus boss with some oogie boogie man from nightmare b4 Christmas music.
Also, I found a level where you wear a propeller hat while in a cat suit while in a ice skate. That's 3 aids at once which is kinda insane.
There are multiple nods to Mario 2 (such as all 4 playable characters with particular attributes, sniffits, slot machines including original, and you're saving fairies) which was one of my favorite in the series.
Lastly, I found the charm level way up above the others. The fairies (which are a welcome change from peach being captured) always entertain me each time they wave a tool and build a new pipe.
I feel like people used to old 3d Mario's may not care for this game, but for people like me who have dis-satisfied with past entries... it's a breath of fresh air.