I was impressed with this team's supplement for the Simic and picked this up as well, and I liked it enough that I'm laying the groundwork for a Simic v. Golgari arc in the understreets of Ravnica for my players. This product hits the sweet spot of well formatted and easy to read while also having a charming handmade feel. The most vaulable feature is an outlining of a Golgari economy based on mushroom farming, glad to give them something to do that's mundane but also evocative.

The only thing I'd want is more, I'll definitely have to supplement with modules of undercities from other settings, but this is a great jumping off point and for the price it is a tier-1 Ravnica supplement.

So i'm rating this product on the price point it gives. Obviously it could go more into the society of the Undercity, give maps, encounters, etc. But for it's price it's fantastic. You get thematic and importantly creative creatures that feel truly unique and terrifying. But beyond being great it does really good world building. Like in this book it talks about the Golgari using the druidcraft cantrip to open and close walls of moss to control the flow of water. That is a really creative use of magic and adds a cool integration of mechanics and world building. It makes the game and the world feel one in the same which is really important for a flavor rich setting like Ravnica.

TL;DR - This book gives you so much amazing and really well made information for it's price, its a steal.