Once upon a time Moby Dick was considered an epic. Now it's usually thought of as an epic fail. I understand the argument, Melville took considerable time getting to the story, digressing every chance he got to educate the reader about some trivial matter, e.g. the different types of rope used on a whaling ship. It's not an easy read. And when you cut away all the histories and factoids there is really very little story left (Moby Dick doesn't even make an appearance until the final three of 135 chapters). But what is left is amazing.
That's not to say that the asides were not worthwhile. They set the mood for the story and were informative—it is easier to believe a story of this magnitude when the narrator proves their knowledge of the subject. Ishmael (and Melville) certainly know whales. And to know that these intrusions were a big influence to Steinbeck in his creation of East of Eden—the undisputed greatest novel ever—makes them all the more significant.
Just looking at the story, though, there is so much Melville did right. The characters are unique and unforgettable. Though we're not as close to Queequeg and Ahab and Ishmael as we may wish to be, what little we get of each is wonderful. And the other characters, human and non, animate and inanimate. Here is a story where the ship and ocean come to life.
The beginning of the novel opens with such a wonderful and touching friendship. From there, the story builds slowly, meanders the huge ocean and then WHAM—death and destruction for all.
I wouldn't recommend Moby Dick for the tepid reader. And forcing anyone—especially a young and impressionable student—to read this because “it's a classic” is likely to turn them from a life of literacy. I think Moby Dick is something you have to feel ready for. After many years of curious wonder, I felt I was ready. And I am glad I finally made the journey aboard the Pequod.