Saw it on HBO. I didn't hate it, but I didn't like it either. It was a romcom, so like you I was not expecting much out of it.
1) It wasn't funny. Other than Ken Jeong, the guy that plays Jian Yang from Silicon Valley, and maybe a couple of other amusing lines here and there, the movie wasn't remotely funny.
2) This Henry Golding guy that played Nick Young is just a terrible actor. It is Ok to cast models in supporting roles, but you can't put one in the lead of a comedy. He was stiff, fumbled several attempts at humor, and isn't credible as the son of the super rich.
3) Nick's sister Astrid was certainly easy on the eyes, but halfway through the movie her plotline starts to take up a lot of screen time even though it is never tied back to the main story. Why do we care about her failing marriage?
4) It wasn't big enough. This is a story about a caste of people that live a life that we can only imagine. The whole movie should have been bigger and more extravagant.
5) My biggest issue is how unoriginal it was. I am not just talking about the plot, because there are only so many ways to slice and dice the Cinderella story. I thought the dialogue was boring and felt recycled. It was like the movie used mediocre sitcom writers.