I think the Zodiac weapon quest gets a lot of flak, but I actually quite like the books (in general). I don't need a Stardust Rod Animus anytime soon since I expect I'll be getting a Laevateinn well, well before I can hope to finish the Animus anyway, but I do like having a background long-term project to keep me occupied. I'll be getting the mythology the books need anyway, and it's nice to every so often have the bit of variety that the book quests throw up - there's been a few times when I've felt bored and didn't really know what to do, and then realised that I could work on a book. I suppose the only thing that I really don't like about the books is that waiting for slow, slow FATEs that require gold participation is a dreadful experience, and the hunting log for each book can be a bit of a chore, but I like how they can send you to out-of-the-way places you rarely visit sometimes.