It is very hard to view the world with anything but pure cynicism after reading the book. Even the title suggests it. Reading about the history and the current troubles of this tiny nation, which has so much in common with the United States, is both depressing and maddening.
This book is a very important read for anyone who is interested in US foreign policy or Latin America. As Farmer says, Haiti is usually not thought of as part of Latin America (indeed, it's usually not thought of at all) but it should be. Like all of Farmer's books, it is extremely well written: it is a fairly quick read that is chock full of information, but it is never overly technical. Someone who is not familiar with the subject or the region (like me, before I read this book) would have no problem reading it.
In fact, I suggest that you keep 2 or 3 copies on you at all times. That way when someone makes an ignorant comment about Voodoo (no matter how multi-cultural and intelligent they're trying to sound) you can hand them a copy and tell them to learn a bit more about Haiti.
EDIT - There seems to be something of a smear campaign going on against this book. The book was originaly published in 1994, and this edition came out in 2003. Therefore, the current happenings in Haiti are not mentioned in the book. One reviewer mentioned that Farmer is so rich because Aristide is lining his pockets. This reviewer is overlooking the fact that Farmer is one of the head doctors at one of the largest hospitals in the US (a post that pays a pretty penny), and teaches at Harvard (ditto), and does frequent speaking tours, is a published author, and much more. Farmer is also quite open about the fact that he lives in a tiny appartment in a very bleak area of Boston, and puts his tremendous earnings right back into Partners in Health.