It's one of Berkeley's weaker films, and disappoints a lot of people because he didn't do his trademark gigantic production numbers (for budgetary reasons or because he wanted to try something different, I don't know). But with all the big musical names in the film, and "Hooray For Hollywood" as one of the songs,
Numbers like these bring home the importance of the moving camera to Berkeley and other great directors of musicals. At Warner Brothers, he didn't use the fluid, gliding camera moves that MGM did; WB was a more editing-happy studio, and did musical numbers with more cuts. And yet the camera is constantly on the move in this number, and one of Berkeley's favorite tricks is to suddenly pan to the side, changing from one composition to another in a split second without a cut. It's a completely different aesthetic from the modern one, which is that the foundational technique of a musical number should be editing: the idea is to create the rhythm of the number through cutting. The ideal of the "classical" musical is to let the song and the staging (the movements of the characters) set the rhyhm, and to try and create the illusion that it's all happening continuously, right in front of us.