A really good book on repentance. Uncovers all the false ways we repent, gives a picture of what true repentance looks like, as well as motivations to repent. The only drawback is one can leave feeling like they have never really repented at all. As with most Puritans, they uncover the deceitfulness of our heart, which can leave someone feeling unsure that they are even saved. I am not sure that is such a bad thing. Carl Trueman said when he was in England he had to convince folks they really were Christians. But when he came to America he had the opposite problem. This book is an excellent antidote to the self-assured presumption of many American Christians who think they can follow Jesus without leading a life of repentance.
As an aside, Watson would have been a beast on Twitter. He is one of the most quotable Puritans.