The late, great Arthur C.Clarke wrote a lot of very fine science fiction, but probably the majority of SF fans would agree that his two finest books were 2001:A Space Odyssey, and Rendezvous with Rama. Both classics, and absolutely spellbinding, leaving tantalising questions which are best answered by the imagination.
The great mistake, in my opinion, is that both books were followed-up! Talk about gilding the lily. It is such a pity, because the answers which were in my imagination (and the equally-valid, but different answers in others' imagination) are all ruined by the above questions being answered in a different (and rather unsatisfying) way. I can't help thinking one obvious thought - it is all spoiled!
Turning to this specific book, I agree that it is very good in parts. The octospider race, their cultural history and their method of communicating is a great piece of SF invention. There are moments of high drama, and it is readable, if over-long. But somehow, for me, it never quite hit the heights. A lot of the dialogue is lame, and it bears so little resemblance to the original Rama that I feel Clarke would have been better off writing a completely separate book.
I am not quite sure what part Gentry Lee played in the writing. Furthermore, the original Rendezvous was Clarke's own work, and he had every right to produce a follow-up. Of course! But he has done himself a disservice.
To sum up, it's good SF, readable, but the ending is a bit of a let-down (unless I am too thick to get it). Too long, and no classic. Sorry!