The Life and Diary of David Brainerd by Johnathan Edwards is a book that I've seen to be highly recommended by many. John Wesley wrote, "Let every preacher read carefully over the Life of David Brainerd". However, I have also heard many people today recommend this book with a side of caution. "Dude. It's intense..." is the usual, followed with "But really good." I can safely say after reading this book that David Brainerd was an intense guy. Brainerd said of himself, "I was from my youth somewhat sober, and inclined rather to melancholy than the contrary extreme." Translation: Brainerd struggled with depression. Edwards saw this as well, but noted the benefits, and stated that "he had a great insight into human nature, and was very discerning and judicious in general; so he excelled in his judgement and knowledge in divinity, but especially in things appertaining to inward experimental religion." Basically, Brainerd's struggle with melancholy (depression) caused him to go deep into the caverns of his own heart and find, then root out sin. He was very sensitive and aware of his own sin.
Here's the question that came into my mind before reading this book: Will Brainerd's struggle with depression ruin the book? I can say with confidence that it did not, but made it all the better. We get a glimpse into a godly man's life and see that he was not perfect, but that he was growing. There is a noticeable change in Brainerd's journal entries from the beginning to the end in his dealings with depression and sin. In the beginning, I was tempted with thinking that perhaps the way he thought was the way all Christians thought about themselves and their sin back then, but throughout the book it became more evident that the way he described himself was no average thing. Brainerd struggled with low thoughts of himself. I got the feeling that it wasn't a healthy thing. He was focusing on himself too much at times, like when he would go a whole week without feeling any joy and living in a state of complete dejection. It is evident that God used Brainerd's natural leaning towards low thoughts of himself for His own glory though. By the end of the book Brainerd was more watchful and aware of his own feelings and was more often reflecting on having his "spirits refreshed and raised". This is one reason why the book was good.
God gave David Brainerd, a strong desire to glorify Christ and an equally strong interest in the things of God. "There is no comfort, I find, in any enjoyment, without enjoying God, and being engage [sic] in his service." That was the heart of David Brainerd, and that is the big reason why this book is so beneficial and encouraging. Brainerd was a man who strove after God in all things. He was a godly man, in my opinion, and one that should be imitated for the most part. A word of caution though: don't attempt merely to imitate or parrot David Brainerd without realizing what he was aiming towards. Another way to put it is that you can not recreate godliness without meeting with the one true God. Don't just live vicariously through David Brainerd, but use him as an example of a godly man who made it his goal and desire in life to live in the presence of God and for the glory of God.
One thing that I felt was lacking in the (auto)biography was the detail of his evangelizing to the Delaware Native Americans. He does mention preaching to them and going to them, but doesn't mention any specifics about the fruit of his labors. Personally I like it when (auto)biographies go into detail about who got saved and how they're doing later, or how a church started, etc. One of the main reasons I enjoy reading biographies is because I get to see God working through a normal man in saving a multitude of people.
If you're on the fence about reading this book, I would recommend waiting until you've finished the other books you want to grind through. The Life and Diary of David Brainerd is an encouraging book and left me in a state where I wanted to know God more. I want to pray more, read more, etc., but at the same time it left me a little disappointed with the lack of detail. I'm not saying that this wasn't a good book or that it shouldn't be read, but that there are other books out there that, in my opinion, are more encouraging, less intense, and better written.