1930's "Moby Dick" is a very, very loose translation of the Herman Melville story. In fact, so much is different, it's practically a different story! It's based more on John Barrymore's silent film, "The Sea Beast", and he's returned for this sound version.
When the film begins, it's obvious that the Captain Ahab in the film isn't the one in the novel. Instead of being a stern, joyless man leader as Gregory Peck played him in 1956, Barrymore's Ahab is a common sailor....more like Popeye or Bluto! He's a fun-loving galoot with tattoos galore and a lust for life. But this happy demeanor does change when he later meets up with the whale, Moby Dick. There's also a romance...and I know most people do NOT think of this story as a romance!! But these aren't the only major changes from the book....the ending is also 100% different!! Apparently, the studio didn't like the novel very much and decided to very liberally change it.
In many ways, this is much more a John Barrymore film than a Herman Melville novelization. On the positive side, the novel is pretty dull reading...and this film isn't dull. But it also misses so much of the point of the story and instead is a showcase for Barrymore's flamboyant acting and personality.
So is it any good? Well, for American Literature professors, it's probably a bad choice of films to watch! Others, however, might enjoy it very much provided they don't care about the source material. The special effects, for 1930, are very impressive and the film captures the look of the 1840s quite nicely. A few scenes were actually lifted directly from "The Sea Beast" (such as when Ahab is attacked by the whale). And, the amputation scene is amazingly vivid and effective. My advice is to watch the film and enjoy it for what it is.