The first Mario & Luigi for the 3DS, and I think they hit it out of the park. The graphics got a nice new style, and the game uses the improved hardware of the 3DS to its fullest, without increasing loading times.
I will say that the gyroscope and the touch screen don't 100% work like I had hoped and that the overworld seems a bit overfilled with enemies. However, I do enjoy the possibility of visiting past boss battles that have become harder, adding more to the replayability factor!