Definitely one of the most underrated Mario games. A wonderful combination of RPG exploration and story-based adventuring, Pokemon-like stat building and turn-based battles and packed one of the more detailed and in-depth Mario games. It also makes Bowser an actual character unlike most games, rather than just a black-and-white baddie, as well as an array of new faces that are some of the best in the Mario universe. Combat feels satisfying, same goes for building Mario, Luigi and Bowsers stats and equipment. Overall it's an RPG that doesn't feel boring to explore, no walking section feels dragged out, and this is a worryingly good amount of story/lore for a Mario game.
Without a doubt the best game I've ever played. Everything about this game is top notch from its writing to its unique areas, amazing soundtrack, fun visuals, a really nice take on the classic Mario story, coupled with one of the coolest gimmicks a video game could have. Playing nearly half the game with Bowser was and still is something completely unique to this masterpiece. The battle system is one of the best I've seen in an RPG, second only to its sequel, Mario & Luigi: Dream Team. It truly is the best game of all time.
My favorite in the series, and one of my favorite DS games. I love how everything looks, I still think the writing is funny, and the gameplay is creative and engaging. I have some really good memories playing this game when it came out, and I still think it's worth playing today. A personal favorite.