Aha, I finally finished! I think this could be read just like the previous book: read the first few and then the last few chapters, and you're good. The middle is just all theoretically supposition about life on the moon and what the explorers 'see' on their trip around the moon. It's a whole lot of detail when I know it's mostly wrong.
I did realize, however, that I have the gift of hindsight. This book is to its generation what 2001 (or maybe 2010) is to us today... We don't know what exists in the seas of Europa, but chances are... they're not quite like Arthur C. Clarke expects. And how silly will Star Trek seem when we can actually explore the stars? Maybe if I would've had this mindset earlier into the books, I would have enjoyed them more. As it is, I still thought there were way too many details about what the explorers were seeing and not enough about the actual story of the trip. I did get some practice, however, in my speed-reading abilities... when I realized I just wanted to get through the book!