I've read and worked through the first fifty pages. I'm glad to see a book written on OSGI as I appreciate an edited, in-depth treatment of topics over a 4 page article on dzone. However, I'm running into some difficulty stemming from errors in the examples, and a reliance on tools that may simplify use for someone familiar with both them and osgi. I find use of the tools hides the details that I, as a student of osgi, need to see. I would fully expect to use them, once I've mastered osgi itself, but using them here is too much "magic" too early on. A similar point is made in the "Head First" books when they say not to use an IDE at first.

I find the style a bit wordy: "You're probably wondering how I knew what the group and artifact IDs should be. Well, it certainly would be nice if there were some sort of search engine that would find these things for us. But since nobody has developed one of those yet..." p. 59
I appreciate a friendly style, but this can be a lot to wade through.

The book could be improved with better introductions that layout the chapter in high-level terms. As it is, you have to walk the path with the author to get an idea of what the chapter is about. It really is more of a workbook that way.

OSGI has many popular implementations and this presents a problem for the author of an OSGI book: which implementation to use? Writing for all, or a substantial subset would be quite a task. In some cases Walls writes examples for three, in others just one. I don't know if some of the problems I see stem from using a different implementation, or from a generic error. The OSGI implementation used is another variable to consider when something doesn't work. A 5 star book would have tested the code across a number of implementations and flagged differences in each example.

Having said that, I'm glad the book was written and don't have suggestions for other, better books. Though obvious [...] makes for a good start.