Please note, everything here is just my opinion

Super Mario Galaxy gets a 7.5/10 from me. The main criticisms are that the movie is too short; it's literally 6 minutes longer than the first one, and in that time, it didn't manage to develop, such as Peach's kinship with Rosalina

Since Rosalina only told the Lumas to go look for Peach if something happened to her, she goes, finds Rosalina similar and when she is rescued by the Lumas (thanks to GOAT Luigi) she goes to the library and discovers/remembers her past, and then the film only returns to this development when she goes to rescue Rosalina.

But there would be a way to fix that, since several scenes in the film that are there just for reference could be replaced with scenes that would be used to better develop the characters, such as the part In the scene where Mario and Luigi become babies, it's clear that the scene is just for reference, even though there's a moment in the film where this part is used to develop the relationship between Mario and Peach a little(I'll talk about that in a moment), They could have removed those scenes and used them to better develop the characters.

One aspect that the film developed well was the romance between Mario and Peach. It begins with Mario giving her a gift and going to look for her, and them having moments together then Mario gets a little embarrassed to talk to her, then they have another moment alone when Fox's ship crashes and when Mario closes the gate so Peach can go save Rosalina, that's what I think The film worked well.

And another relationship that the film presents is that of Bowser and his son, Bowser Jr. Their moments, I found cute, I just thought Bowser reverting to evil was a bit rushed, but I think he'll He would return to being with his son, since he shows great affection for him.

Overall, yes, the movie is good, especially for watching with family or friends, it has its humor, in my opinion one of the highlights of the film.