I've been on a literary medieval epic bender recently. At one point I even got some of the books confused but I think I've sorted it out now.
Hilary R.R. Mantel's fantasy world is vivid and complex, sometimes more convincing and sometimes less. I can vouch for the dragon biology which is pretty accurate, and of course the vicious winters that last for years or decades will be familiar to British peasants of any age. On the other hand Mantel seems a little too fond of graphic beheadings, and the idea of a King who would overturn a religion and risk triggering both civil and international wars just for a mistress who is playing hard to get seems a little far-fetched.