I haven't finished yet - 60% through. As I've been reading I've been wondering why some suggested this would not be a good fit for Travel/Adventure. It's a much better fit than I had thought when nominating it.
The story itself does get bogged down by the descriptions, catalogues and history/scientific lessons. It's possibly why I haven't finished yet even though I thought I'd given myself enough time. I usually find it hard to read non-fiction quickly.
Strangely enough, I have a tough time thinking of it as science fiction. When there was a complaint that we were going to be reading yet another science fiction book, I had to stop and think about it. It hadn't even occurred to me that it was science fiction when I nominated it - all I thought at the time was underwater travel/adventure story. It may be because the notions of submarines, electrical power and underwater exploration are so common to me that I just failed to see it. Actually, if Verne made this science fiction feel so commonplace to me, he must have been a pretty great science fiction writer back then.
The only character worth knowing is Nemo and he is pretty interesting throughout. The narrator is for the most part a travel writer with a scientific background and not worth exploring as a character at all. The rest are not really worth much either.
I haven't got to any real drama yet other than the shark fight, so I'm expecting it to become more dramatic fairly soon.