How reliable was Foxe's "Book of Martyrs" by John Foxe?

I have not read all of it yet, but I have read quite a bit of it, and I believe that Mr. Foxe was an honorable man, problems notwithstanding. I believe that he tried to relate the best that he could about what was going on in what was considered to be Christendom, at the time. I believe that the man was telling the truth.