Review
I bought this book hoping it would be helpful for the Solomon Islands. There was only about 30 pages about the Solomons. This book is a great guide for Papua New Guinea. I would suggest looking for older guides. I bought an older guide from lonely planet that was strictly about the Solomon Islands. It was much better, only the finacial info was definitely out of date.

Wish there was more information about various locations
The book does not really give sufficient information about the villages which are, in fact, memorable experiences. Nonetheless, I am not aware of a better source for information about places in PNG and so recommend that someone traveling to PNG buy this book. There are a few other good books about the culture and art.

A Very Poor Guide! :-(
Once upon a time, Lonely Planet had a good guide to Papua New Guinea (371 pages), and an excellent one to the Solomon Islands (279 pages). For better or worse these fascinating countries don't exactly attract hordes of holidaymakers, so after leaving those books unupdated for many years, the publisher has now decided to dump them together in this new edition (272 pages).
The result is basically a new, much slimmer guide to Papua New Guinea, with fewer than 30 pages on the Solomons (where it only actually covers half the country even nominally).
Not only has much of the detail been thrown out, the quality of information has also gone downhill sharply! :-(
The authors have very obviously never visited even major tourist destinations of PNG described in the book - as confirmed by owners of accomodations included in it, who told me they had merely received phonecalls from the author who didn't even visit most of the Sepik Region or the Highlands, for example!
Much of the "updating" seems to have been done by surfing the web, and as a result the book abounds in recommendations for expensive, upmarket places and tour-operators that do have websites, while completely ignoring cheaper, budget guesthouses which have no info on the net. Even excellent, small locally owned places that were in previous editions of the PNG guide are conspiciously missing! And as for what the authors consider "budget": their itinerary recommended for budget travellers includes staying at a 150 USD/night resort!

This book is a real shame to Lonely Planet.
If you are planning on resort-hopping on a short holiday, it will be sufficient, but if you want to explore these two countries in depth without spending a fortune, you are far better off trying to find copies of the now out-of-print old editions, which still contain far more useful information than this new guide.
Check Amazon for reviews and availablity of the old Papua New Guinea guide and Solomon Islands one.

Another cheap little book that may well enrich your travels in either of the two countries is LP's Pidgin Phrasebook.
Those keen on getting way off the beaten track in PNG on foot will still find Bushwalking in Papua New Guinea invaluable!