While Super Mario 64 is considered one of the best Nintendo games of all time, the sequel Super Mario Sunshine was not as adored as it's predecessor. I loved Sunshine, and I will even say I liked it more than Super Mario 64. Though the FLUDD water jetpack did make it a lot different than it's predecessor. I was ironically happy to see Super Mario Galaxy be a little more traditional.
The game was more like Super Mario 64 except Mario could travel in outer-space (they never explain him not needing a space-suit) and travel on tiny planetoids but also larger areas as well. There were some new power-ups like Bee Mario but Mario had to rely more on platforming without the aid of a tool like the FLUDD from Sunshine.
There were also some cool levels that were wacky and didn't make much sense with the "galaxy". It was a joy to play but it also provided some challenges for Mario fans. It still showed that after many decades Mario is only rivaled by few.