Lots of information that you need to be aware of to build RCP applications. I didn't find it particularly engaging to read, and unclear in parts. I didn't like the way they introduced deprecated or non-preferred ways of doing things before the preferred ways in a few places. Why waste the readers time? I thought the use of screen captures of the eclipse outline view to show the methods of various API classes was just lazy - that's text, and would have been easier to view in electronic form if presented as such.
When making RCP applications, this is a must have desk reference.
Its a bit lacking in some detail here and there, but its the best of the bunch.
RCP can be a complicated topic due to a fairly Byzantine class structure, hence be prepared to draw from a number of different sources in order to make progress, and this should definitely be one of them.