It could have 1 more star.
It's a classic. It had much specific knowledge about film-making, and it bore many details of the Golden Age, such as story-telling, a pair of detective-supporter, one is clever and the other is silly. The story started straight into the murder, also a good point, but from that, it was somewhat rambling, even though I can easily flow with the plot. I think it should remove a few unnecessary paragraphs to focus on the main events, which were the murders.
The supporter, a reporter, which was a new detail comparing with other stories, where they are normally military-originated (look at Dr. Watson or Hasting). But I believe this reporter should not be working for any paper, for his rather slow-wit and easily distracted by a pretty girl. The main detective was a scientific, disciplined man who used scientific achievements to analyze the case and find the culprit(s). Problem is, the author let the science get overdone, therefore there wasn't much left for the process of deduction. I can easily follow the explanation, the chain-links in the logical reasoning of the detective until the end, which is the spot for scientific analysis to step in and finish the job (which is the type of work for official forces, even nowadays). This process made the story to be more realistic, but at the same time took away an opportunity of logical deduction, which is a key detail for the peak near the end. From that point, anyone can be the murderer(s), and it entirely depended upon the author to select among the suspects because he withheld from the readers the keys to unlock the mystery.
The ending stopped at exactly the point the name of the culprit(s) was announced. I felt it was rather cut short, as it should be more, for example about the events after the revelation, about the remaining people, how they coped, how they moved on with it. This type of ending I have met before, but in this case, I believe it is not suitable.
So, is it a fine book to read? Probably yes, but not a recommended one.