Super Mario Sunshine is truly an amazing Nintendo game. It was my first ever Gamecube game, and probably one of my favorites in the Mario franchise. I think the best part overall is the concept; The entire game is themed around Mario's vacation, located on the Isle Delfino. Instead of stars, you obtain Shine Sprites. All of the levels are based off of places incorporated all over the island.
Like many of the other reviews mention, it is a lot like Super Mario 64, but with a different idea and a little more modern. It's really hard for me to choose between the two games, but since I played this game a lot more growing up, It does hold a special place in my heart.
The gameplay and story are well-written, and it does take quite a while to collect enough Shine Sprites to battle Bowser at the end. The only thing I could say was being really disappointed with what was the final battle, which is wayyyy too easy. I can usually beat it every time without even losing a life. Also, once you beat the game it just takes you back to battle the final boss again..It would've been nice to see something besides that happen at the end.
For the levels themselves, they're very fun for the most part. There are definitely some that are annoying and challenging, but it's enough to keep you satisfied for sure!
You're definitely missing out if you haven't tried out this Mario game yet.