I've not read this edition, so if there's any other reviews ignore this one, but until then take note:
The previous Lonely Planet for these three countries was shockingly, shockingly awful. These are difficult countries to travel in, so I'd recommend taking at least one backup guide book, especially for Azerbaijan.
Azerbaijan with Georgia (Trailblazer) is fantastic, and it's few pages on Georgia at the end were better than the previous Lonely Planet's entire Georgia section.
Hopefully this book will be better. There's a different lead author which is a promising sign.
Just to give you an idea, the previous book's section on Georgia was so hysterically wrong it was a running joke among accommodation owners ("Ha! You read that in your Lonely Planet did you?" "Erm, yes, sorry..."). To give some examples, it got the dangerous lawless regions wrong (!!), described a dingy basement as an attractive garden, and called an old bathhouse something like a 'refreshingly social cultural experience' when in fact, it was nothing but a room where naked overweight women whose houses don't have showers stand while being literally hosed down with cold water - as functional a place as a laundromat but more grim, and understandably awkward when curious foreigners are around... I doubt that there'd been any actual baths there since before the USSR.
As for Azerbaijan, we gave up on the book on the first day, and later heard that other people's copies of the book had been confiscated on the border. It's history section was so crude and slanted it was actually considered insulting. The Armenia section was at least accurate (if vague), but wrote about nothing but churches and how to get to more churches.
Basically be careful and take a backup. Looking at the contents page and the cover (Kazbegi, one of Georgia's many real attractions, unlike the last book which had just some random and fairly trivial church), it looks like more effort went into this book, but I still wouldn't wholly rely on it.