I'm a fan of both games. Why exactly do you say that?
Mario Odyssey's "999" power moons were nothing more than a gimmick. several of the power moons are bought in shops. Many are obtained through multi-moons. A bunch of them are just lying around in random places, and many are just the same thing as another moon somewhere else in the game. The only parts that are actually challenging are the levels where the game takes away cappy, which just goes to show how broken he is. you defeat almost every enemy just by throwing your hat at it. Most of the worlds are just twists on new super Mario bros worlds, eg. grassland with dinosaurs, desert with ice, lake with mermaids, snowy area with underground village, jungle, clouds with literally nothing other than clouds. There are some unique worlds, such as the grey world of cap kingdom or the realistic vibes of ruined kingdom, which is just a boss arena (lost potential). I just didn't find it all that fun and found the reasons why. Also, "Nostalgia" doesn't justify the gameplay. It seemed more like they were just reusing ideas and assets from old games instead of coming up with new ones.
However, Peach and Bowser getting married again did help spark the idea for my paper Mario fangame, so I'll give it credit for that.
