I just finished the major research phase for the story, and the most surprising thing about it was that I didn't completely hate it.
I don't read much non-fiction, but between late February and early April, I borrowed over 20 books from the library on a variety of topics ranging from medieval clothing, food and architecture to rats and how to get rid of them. I learned a lot. I didn't do much in depth reading, instead copying tracts of each book so that I could have them available to me when I am editing relevant sections of the book.
The best thing about the research is that I learned about topics I might otherwise never have delved into. I have a short attention span, but love learning new things. The major advantage I see to novel writing is the ability to explore almost any topic I want, and all the little side things that aren't central to the story, but add realism. Neat!