Courtney and I finished up Super Mario Sunshine (with all 120 shine sprites) over the weekend. It was my first time playing the game. It was pretty enjoyable, but I have my issues. I'm a big fan of Mario 64 so I compared it to Sunshine a lot while playing it. Sunshine's levels sometimes went on a bit too long. 8 shine sprites, and an additional 2 hidden ones, seemed like too much. Also, the blue coin collecting got really monotonous. On top of that, it never really felt like you needed to collect the shine sprites. If it was unlocking levels, you had no indication.
The FLUD mechanics were cool and it was a great looking game which was nice. I really enjoyed the Piantas as well.
But after getting all 120 sprites, and getting nothing but a different end credit picture for it, I came out of it a little frustrated.
tl:dr, Mario Sunshine was enjoyable, but Mario 64 is way better to me. More levels and getting stars to unlock them made it more fun.