Beginning F# goes through the basics of F#. You'll get an basic understanding of classes(and methods, properties, constructors, etc), list handling, control flow, imperative programming and some F# specific libraries.
However the really interesting F# stuff -- event handling, reactive programming, workflows and message passing -- are only briefly explained. I guess it really is a book for "Beginning F#", but I somehow hoped for more. Lots of pages are spent on showing how to do WinForm GUIs, and listing the WinForm's API, something I think is just a waste of pages.
Pickering claims that you don't even need a programming experience, although experience of either C# or VB.NET "would be nice". I would strongly recommend a working knowledge of C# or VB.NET, or at least an OO language; not much time is spent on explaining such basics.
I'm still looking for the ultimate F# book, the book that expects you to have a firm understanding of C# or VB.NET, and goes through how F# does those things, but most importantly the things only F# offers.
All in all, the book isn't bad, but it really is just for beginning F#, you will soon ask for more.