There's no doubt that Sober is one of the best working philosophers of science, and this discussion of parsimony is hugely useful to those who are wandering into the depths of both philosophy of science and epistemology. Sober actually sells short the epistemological importance of his work, and the work of his colleagues, because a lot of the framework for justification that he provides in the book can be extended well beyond just the philosophy of evolutionary biology that he offers and out into giving accounts where the historical data is seriously limited.
There are a few problems in the book, and they are problems of philosophical writing generally that haven't been altered in recent years. The first is that it's hard to tell who Sober's audience is in putting the book together. He dwells in the early chapters on some general material in philosophy of science that should be familiar to any philosopher reading, but he then jumps with full force into an incredibly complicated discussion of both the biology and more technically advanced philosophy. For those outside of the more narrow subfield, this can cause some serious literary problems.
There are a few opportunities where Sober takes his time and slows down and really illustrates his points, and in those moments it's clear that he is a terrific writer and educator, but it's not consistent throughout the book. This is partly because the book is kept to a relatively short length, which is understandable, but unfortunate since the material in the book is advanced and deserving of the more delicate exploration.
All around, this is a solid read and definitely one worth getting into for those who (like me) are really interested in the philosophy of simplicity. Also, those who are routinely confronted with objections to "historical science" that have become popular in Creationist/Intelligent Design circles, it is hard to find a more powerful philosophical source for explaining historical justifications and the epistemology of that sort of science than Sober. While, perhaps, this isn't an appropriate introductory work, it is a useful piece to be aware of.