Moby Dick is a humongously long book and takes quite a bit of sustained concentration to get through, but the rewards of such an endeavor are similarly huge. You will be forever enriched by the detailed description of Ishmael's reasons for going to sea (whenever he feels a damp, drizzly November in his soul and he fears he may just start going about methodically knocking people's hats off. You will understand his fear of his first roommate, the cannibal Queequeg, and you will be delighted as his fear turns to undying affection and respect as he realizes this cannibal is more civilized than most church-going seamen. But wait -- we are only through chapter 16 of 135 chapters! We haven't even gotten to Ishmael's description of the mad Captain Ahab or Ahab's true goal, the white whale, or even the steady, patient first mate Starbuck (whose name was later used by the ubiquitous Starbucks coffee chain).
Moby Dick can be a tortuous read (especially if you are being forced to read it for a college class as I was the first three times I read it), however when read for pleasure this book brings unheard of delights of description and satisfying details you won't find anywhere else.
So don't be afraid of Mody Dick. Take it slowly. Be sure not to skip past any words you don't know (I guarantee there will be plenty of them even for the well-read reader). If you savor it, scenes from this book will stay with you for a long time after you finally put it down.