Just finished reading the book by Vincent Starrett, I watched this (on YouTube) and was unimpressed. The basic plot was similar to the book, but the screenwriters changed too much for me to accept. The book's amateur sleuth was a young film critic (not a mystery writer) and he was younger than the actor portraying him, and much less confidant.
The book is set in Chicago and Wisconsin, not California. The culprit is sort of the same, although a lot of the details in motive and exposition are different.
None of this is damning to a movie, but the film itself is too scattered to gel completely. (The whole New Year's Eve party was a silly insertion, not in the book.) There were a few things I thought were silly (like having a hotel room closet that had a lock on the outside. Huh?)
If I hadn't just read the book I don't think I'd have stuck out the entire 109 minutes runtime.