I've read all of the AssCreed novels (Renaissance, Brotherhood, The Secret Crusade, Revelations, Forsaken and Black Flag) that came out. I loved the Ezio and Altair parts (novels 1-4). Forsaken and Black Flag were so-so for me. I think that is because the author is a specialist in the Italian Renaissance era and those last two periods are very different (American Revolution and the Age of Piracy). I have to admit that I haven't played the games (I need someone to donate a console for me), but I have read some comments on the webs saying that the novels gave a much deeper understanding of the characters and the secret of their motivations that were not touched/mentioned by the main games.
Revelations was the most memorable one for me since it mentioned things that are not in the game like
how Ezio proposed to Sofia (I was giddy after reading that) and his plans after that made Claudia flip! Plus the whole transcript (I think) of Embers is there too, including that beautiful letter that still makes me emotional up til now. /sob
So far, I haven't gotten my hands on the AssCreed comic books cause even the novels need massive amounts of searching across numerous bookstores just to get my hands on them.
I do recommend them, even for people who have no idea what AssCreed is.