Interesting review. The first few paragraphs are quite scathing, but once it gets to specifics it's quite heavy handed with it's praise. I've only started reading and I have to agree with the overall feel of the review.
People who will hate this book:
* Established fans who are playing in the 3e era.
* Established fans who are playing in the 2e era.
* People looking for crunch.
This isn't because the book is useless as an overview of the region that can be used to run a game of any time period. It's because 3e and 2e fans likely already have products that detail the regions to a much higher level of detail.
The crunch is little more than a token effort and IMO is not a good reason to plonk down $40 USD if the only thing you are interested in is the crunch.
People who will like this book:
* Established 4e fans running games in the Sword Coast region.
* Established fans running games in the 5e era who are anxious to find out what's changed (SPOILER ALERT: Read the 3e FRCS and chances are you'll have an accurate picture for 75% of the Realms).
* People who've never played in the Forgotten Realms and are either playing in it or want a book filled with settlements they can insert into their homebrew world.
If you go into this book expecting a 3e/2e/1e style of supplement you'll be disappointed. If you go into the book expecting a 3e/4e level of crunch you'll be disappointed. If you go in wanting an overview of the Realms and some inspiration for updating the 4e Realms to a post-Spellplague state, you'll likely be happy.
Note: I've only started reading so this is just my initial view and it could change the more I read.
As I've said elsewhere, this is a player's guide. People should be comparing it to books like 3e's Player's Guide to Faerûn and 4e's Forgotten Realms Player's Guide, not to campaign setting guides.
This is only a first impressions view, but I strongly disagree. There is not enough crunch in this book to make a comparison to the 4e FRPG a favourable comparison. Unlike Pathfinder or 4th Ed this is not a book where everyone needs to own it. This is a "maximum of 1 per table" supplement. I'll be advising my players not to buy it. Any fluff they want I can put on the campaign wiki. Any mechanics they want I can let them copy from the book in 5 minutes. If someone is ultra desperate to read it, they can borrow mine for a couple of weeks (with the caveat that all descriptions of outside the Sword Coast are based on rumour and hearsay and do not present an accurate view of the region).
This book (again, first impressions) most definitely embraces 5th edition's less is more philosophy. While that might be great for mechanics, fans of 3e supplements or 2e supplements will be sorely disappointed. This is aimed squarely at brand new fans with some limited appeal to fans of earlier editions.