My main problem with this book is Coby sets up to prove that Cromwell followed Machiavelli's teaching in The Prince and to do so reads all his actions trough Machiavelli's prism. But this methodology is risky: one often ends up forcing facts into the model, regardless of other possible (if not more plausible) explanations.
I read this book back-to-back with Schofield's biography and I found Coby's account of Cromwell's life and his death not only biased but unsubtle. Nothing new is added from what we know trough popular culture, which is a pity, and I was surprised by the author taking things out of context: most notably, the use of the word "Catholic" in the scaffold speech, taken to mean the Roman Church and not the use it was given in Lutheran circles in the 16the century.
Lastly, and something always important to me, the scarce bibliography was frustrating and something I always dislike in non-fiction books.