The best Mario RPG since Super Mario RPG: Legend of the Seven Stars.
Let's start with graphics. It has that Mario & Luigi style of art that we know and love from the first two games, and it still hasn't let down. It's colourful, clean, and vivid. Nothing more to say.
Next is sound. The sound effects are awesome, of course we expected that from a Mario game. Everything fits! As for the music, it has an enjoyable soundtrack. Everything is good, and definitely has some standout tracks in it. The only point in the game not quite as great as SMRPG.
The gameplay. To play this game is to feel heaven at your fingertips because it's so enjoyable that you don't want to put it down. The challenge is at the perfect level where it requires some time to figure out a boss but not forever. The controls are perfect; no qualms about gameplay at all.
All in all, if you enjoyed any Mario RPGs before this, you'll definitely enjoy this one.