The first couple of chapters are generally pretty helpful in terms of various suggestions as to what to consider when deciding a pantheon (eg, a proper mix of portfolios, alignments etc...) and then in actually defining the power levels of the deities down to their individual stat blocks.
Having said that, you could very easily get by without this book. I would imagine that over 95% of campaigns never get to the stage where a deity's stat block is important. So I'm sure that with a bit of imagination, perhaps fertilised by some creative plagiarism, you could easily design your own pantheon without having to resort to this book.
After all, all you really NEED for each deity are:
- Symbol(s);
- Domains;
- Favoured weapon(s);
- Portfolio(s); and
- Alignment.
After that, you may want some flavour text for the deity's history, information on churches and sects, that sort of thing. Check out Faiths and Avatars for some ideas.
Cheers
NPP