I don't think you can read this book and make sense of it if you don't work in Finance.
But if I'm wrong and you can, that would make it my favorite book on the crisis. For the sake of keeping score, I rank this anonymous hedge fund manager above Joseph Stiglitz, Andrew Ross Sorkin, Robert Schiller, Alan Blinder, Neil Barofsky, Anatole Kaletsky, Simon Johnson, the lot of them. To say nothing of Matt Taibi, Michael Lewis, Jeff Sachs, Hank Paulson, Paul Krugman and the various other guys who have an axe to grind (much as I have thoroughly enjoyed some of their work).
The arguments are analytical, dispassionate and very clearly thought through. I found it impossible to disagree with anything the guy says and even on the bits he ultimately gets wrong I swear I can remember that with the information available at the time I was arriving at similar conclusions.
The book is proof, if anything, that markets at some level work: exposure to the market makes you think and analyze, it forces you to get to the bottom of what's going on. Ah, and it keeps you away from the extremes.
I particularly enjoyed reading what the author had to say about Simon Johnson's brave and inventive but ultimately flawed article in the Atlantic.
There are two things the book does not do: first, it does not have any particular order, it is not a narrative in any way shape or form like Sorkin, Blinder or Paulson are; second, it does not attempt to explain why it all happened in 2008, what was different in the last 20 years that did not hold true before.
For that, you'll need Stockman, which is however a very difficult book to read and an impossible one to enjoy.
The "Diary" has strengthened the faith I have in markets.