I was waiting for a long while for this book to come out, and at long last, it's here with us, and it is the single greatest 3rd party D&D product I've gotten my hands on, easily rivaling (and frankly surpassing) a lot of the official material in terms of quality - the art is beautiful, the writing is stellar in being both expansive yet actionable, inspiring and concise, the layout is great, and the PDF is very accessible, with full bookmarking, alt text for every image and toggleable layers.
The book delves into a lot of topics that were either left out, misrepresented, underexplored or bogged down by executive meddling in previous sourcebooks for the setting, and here in ExE, Keith is finally able to give them the spotlight they deserve, with plenty of interesting material for both players looking for new character ideas (both in mechanics including new races, subraces, subclasses and spells, and in lore) and GMs and adventure writers looking for plot hooks and new campaign concepts, monsters to use, and items to hand out.
If you've ever wanted more information on the unique Eberron cosmology, how the Last War was actually fought, what's up with nations like Droaam, the Dhakaani and the undersea denizens, or just what the hell this whole "wide magic" thing actually means or what the Blood of Vol is actually like from an unbiased perspective, this is essentially a must-buy. You don't even need to be running Eberron in 5e to make use of the majority of this book - though there is plenty of neat rules content, it is a lore and worldbuilding resource first and foremost.
I've still not fully made my way through it - it's a massive book, longer than Rising from the Last War in pure wordcount, and every page that I read inspires at least one (and often more) ideas for characters, adventures and perhaps entire campaigns, and it's well worthy of the price point. While I cannot afford it in hardcover, I am certain that it makes for a very worthy addition to any Eberron fan's bookshelf or digital library alike.
[5 of 5 Stars!]