No plot description; I've already written one for four other reviews of versions of the movie, and besides, everyone knows the basic story anyway.
When I first saw this version of the classic story, I'll admit I was blown away, particularly by the savagery of Fredric March's performance as Mr. Hyde; he is truly a scary, brutal creature. I also liked some of the visual tricks in the film, particularly the opening sequence where we see all the action from the point of view of Dr. Jekyll (including a nice little moment where he checks himself in a mirror). It is probably the best version of this classic tale (of the ones I've seen anyways). However, it is one of those that one watching was enough for me; though I do admire a lot of things about it, I just don't actively enjoy rewatching it, and I get very little that is new from the experience. Part of it is probably the fact that there are so many versions of the story out there, and most of them are so similar in story construction and there is so little variation on the basic plot that the story has lost any sense of novelty for me. That being said, if you haven't overdosed on the story, this might be the first one you would want to see.
And I'm also reminded that with the five versions I've already covered, I still have the Spencer Tracy version to look forward to in the future. After that, I'm hoping some of the later versions of this story offer some fresh takes on the story.