First, a declaration of interest- Beer with Teeth play in my RuneQuest, and as they've borrowed one of my House Spells, I get an acknowledgement, but no money has changed hands (I barely even get a cup of tea off them while I GM!)
That said, I can heartily recommend this guide to the low class area of the City of Clearwine, although it can easily be used with minimal adaptation to most Sartarite cities, with a bit more work outside Sartar, and even (if you can survive without Ducks) outside RuneQuest.
What is it?
A nicely detailed write up of the sub areas, main inhabitants, and relationships of this poor area, with fully statted and motivated key NPCs, with relationships between them detailed, to say nothing of the superb artwork by Kristi Herbert. Each sub area has plot hooks, which should allow most groups to be drawn into the possibilities of the street level game. There is one more developed plot, which I haven't looked at, in case I get spoilered.
What isn't it?
Because your Glorantha Will Vary, it is assumed you as GM should be able to tailor the plot hooks into stories for your group, and suiting your campaign. They are not fully developed, but that is not the intent of this book.
Why should you get it?
Because you never know when you'll find your players hiding in a slum, and it's handy to have a ready made slum ready to drop them into. It may even be in Clearwine. And Devolin may even have a cunning plan to get them out of there.....