I dunno, I had a great time. So much going on all the time, even in the Describing Whales chapters. Yes it felt scattered sometimes because the whaling stuff kept jumping in and I'm sure there are deep Great American Novel reasons but I didn't approach reading it from that perspective (because I read it on my own, purposefully,) and I still had a great time (or maybe had a great time because I didn't read it that way?) 

The introductory essay in the edition I read, by Carl F. Hovde, I think helped me in approaching the question of narration/who is narrating so I wasn't bothered so much by the flipping of forms and narrators (and I'd recommend just reading the Whale Parts, before the final chapters where you actually get to the titular whale, as Herman Melville explaining to you that Whale are Fish and moving on from that point, because it makes them so much funnier.) 

I'd love to read like more commentary on the novel now that I've had a chance to just like enjoy it and vibe with it, but all of that aside I just had a great time and I do recommend reading it just for fun.