As usual, it depends on your playing strength, and what you expect to get out of it.
Here are a couple of reviews: http://www.chessvibes.com/reviews/review-the-alterman-gambit-guide-black-gambits-1 http://www.chessvibes.com/reviews/review-the-alterman-gambit-guide-black-gambits-2 (note that the reviewer is an IM)
I think the book mostly starts its analysis after move 10 or so, and then spends tens of pages per line. The book is only useful if you can actually get to those positions (if your opponents deviate earlier, it's useless) and if you know how to deal with reams of analysis. Probably useful if you're at least 2200+ over the board.
Is this a good series i.e. worth putting money into?