Personally, I found the book distinctly disappointing. If you already have some level of detailed knowledge about the common file formats, it's little more beyond glorified POD. You already know that JPEG encodes images in 8x8 blocks using a quantized DCT and what that means? Then you won't get anything out of this book.
For those who have very little background in the subject I can see it being useful, but those more intimate with the subject will not get anything for their money. I recommend you leaf through the pages and sample a few chapters before you buy it. You will most likely quickly notice whether you can get anything out of it.
Makeshifts last the longest.