Music: I thought the songs were not that memorable besides the main song that they play during the sad scenes. That one sounded pretty good. I did some digging and found that the song is called 时间煮雨 (Time Boils the Rain). The song is originally sung by Kris Wu (lol ikr, I was surprised too). Links to the songs:
Kris Wu: https://www.youtube.com/watch?v=Wp-wyHzQx4k
Movie/Girl Vers: https://www.youtube.com/watch?v=VK5nEJCS2HQ

Acting: I thought the cast was pretty good. Watching the NGs at the end of the movie, you can see how well they bonded irl. Everybody in the movie was so good looking (although some outfits might be outdated now). I kind of wished they fleshed out the Wan Ru's character more though. I understand that she's kind of the the comedic relief one (who still gets her share of sad scenes and drama), but like I sometimes feel like she's just there for the other girls to laugh at... I guess she's kind of like the heart/innocence of the group (even though Lin Xiao and Gu Li seem to be the core of the group). Kai is good looking af in this (all the guys are lol, but Kai was my fave bc his character is literally the epitome of dream husband). Everyone acted pretty well in this!

Plot: A weaker part of the movie. Honestly, the best part about this movie is the bond that the four girls have. It is not a deep movie though. I recommend watching this if you are just looking for a movie to cry to but still feel good about at the end because there's a happy ending for everyone. I read the comments saying that the ending is super sad because everyone dies in a fire? Maybe I watched a different version, but the end was supposed to make it seem like something bad happened, but the audience is just tricked into thinking that. The girls have all since moved out, but they get together once a year at that old house to celebrate their friendship. That was what I saw happen. Anyways, the lot (and I mean A LOT) of the plot in three of the four movies could simply be avoided if these "besties" just talked to each other. This was what made me angry while watching sometimes. If this movie is supposed to show how these girls are so close, then how are they so oblivious to each other's body language?! Like how can you not tell when your BFF is lying or feeling sad-- especially after living together for like 4+ years??? If they are BFFs, then they should help each other through problems, not lie about stuff and then have it all blow up in their face later. If anything, they are just a group of people who have a really high tolerance of forgiving each other for stupid things that could've been avoided in the first place lol. But I still cried in some scenes because the actors/actresses were good at convincing audiences of their pain. Also, I can kinda see where the criticism of this movie being too materialistic comes from. It's like these characters live in a separate world. They pin it all on Gu Li being rich, but even the dorm they lived in in the first movie looked like a studio flat only someone with six figure salary could afford. However, this is a "chick flick," so the critics also don't have to be so particular...