I will say that if you're not into old Hollywood you might not like this movie or might find it bizarrely excessive in its depictions. I didnt necessarily think the costuming was 100% period (esp Margot Robbies hair), but I do think that was their choice and it def made it fun.
Visually its stunning in a Baz Luhrman-esqe way.
The standout story for me was the transition from silent to talkies and the toll it took on the actors (brad pitt does a good job with it). Like Manuel says early on, he wants to see a movie set and be part of something bigger. I think thats the point of the film and the individual roles people from all walks of life and races played in it.
I didnt find the length bothersome, rather more necessary to tell the story right. I was sad when it ended actually.
I loved that they wove Louella Parsons persona in, Anna Mae Wong, Thalberg, the studio coverups. Give it a go.