I felt this way about it when it was released. It is listed in some lists as being one of the best Mario games but I totally disagree. Despite having a very limited library of games at the time, this one got relegated to obscurity pretty quickly mostly because I hated the focus on the water canon that would run out so often.
I understand that they were trying to be constantly innovative with the Mario franchise and didn't want to just release another clone of the epic N64 game, but in my mind they really missed the mark with this one.