Disclaimer: Manning Press and Michael Ford very generously sent me a free copy of the book.
One thing that always slightly annoys me when I'm reading a book about Python programming is having the first few chapters devoted to introducing the Python language. However, I'm sure experienced .NET people felt the same while scanning through the introduction chapters to .NET, which was totally new to me. (I'm also glad there was an appendix about C# syntax; I learned that C# seems to have invented a new syntax or keyword for every possible programming paradigm.) IronPython in Action seems to do a very job, overall, of catering both Python programmers tiptoeing into IronPython and .NET and C# developers finding the light of dynamic programming.
I would have appreciated a chapter or section on parallel processing, since IronPython offers much better threading and concurrency primitives than CPython. Perhaps an example where IronPython can perform a task that would be impossible on other implementations of Python is in order. I want to see how .NET can make concurrency easy and pythonic.
Before reading this book, I had dismissed .NET as a non-cross-platform hunk of Javaish APIs. I see now, though, that IronPython is able to combine the beauty of Python with some of .NET's better APIs (I would still rather use PyQt for GUI programming. Windows Forms has not improved.) to make a powerful development platform.