I'm a big fan of Mosher's. I think Radical Brewing and Tasting Beer are very entertaining reads on their own and both are valuable as homebrewing books.
That said, they aren't precisely fantastic reference books for describing the process in technical terms. One of the reasons I like Mosher is that he doesn't focus on technical areas as much as he promotes a more artistic approach to brewing. He inspires greatly.
I'm in the middle of Mastering Homebrew, and I can say I'm disappointed with it's lack of humour. When you expect the lighthearted touch from his previous 2 books, and you don't see it, it's disappointing. I'm not sure if he is making a conscious effort to tone it down or what, but it's more straightforward than his others.
It also goes more in-depth into the brewing process than his previous books. Mastering Homebrew could be compared with Complete Joy of Homebrewing, or How-to-Brew, but with more graphs and charts.
My criticisms so far, beyond the lack of good humour, is that Mosher has remarks that seem counter to more modern understanding of the hoembrewing process. For instance he cautions about Hot Side Aeration, which, while not exactly being non-existent, is probably not worthy of consideration for the homebrewer, at least according to several well-known sources. I think there were 1-2 more items that slightly irked me, but really not big things.
I'm about half-way through it now, so there is a ways to go.
