The book is certainly an entertaining rollick in the mind of a man who was important but is largely forgotten about today, a regular Wall Street genius who for a time seemed to screw everybody as he looked out for himself.
But here's the thing - that image was a deliberate creation of the author, who despite what the editor's note might say, was definitely not Daniel Drew. The book was written by Bouck White, a radical minister and socialist who was kicked out of his own church. White was attempting to show just how evil the men of Wall Street really were, how hypocritical they were in professing faith while destroying lives via the stock market. In that way the book reads like the diary of a truly evil man, whose actions and words will often shock and amuse. In fact the book gets to read as something of a religious parable, where the evil man is ultimately taken down by his own greed and the equally evil men he made his 'friends'.
And it is a total fraud. The diaries White claimed to have received from a grandniece of Drew don't exist. What stories in it are true were taken from other books (sometimes almost completely ripped off) and newspaper reports. Much of it is unverified completely, and any of the personal thoughts of Drew contained in this book are fully fabricated by an author who despite his efforts is ultimately just as much a liar as Drew was.
In the broad strokes, the book really isn't completely false, although it may help a reader to read the appendix of the much later book "The Money Game in Old New York: Daniel Drew and his Times" which points out several glaring errors and outright lies contained in this book. It really is more interesting as a way to look at the image of Wall Street brokers of the time - a better look at what Bouck White was supposedly revealing than what he actually revealed. And besides all the errors and false history, it is as remarkably readable book for having been written in 1910. Just don't mistake it for actual history.