Mor is an ancient ruined city in the nearby swamp, crawling with humanoid factions. Lesserton is the nearby town and home base used by scores of adventurers to plumb the ruins; it's literally "the adventurer's paradise". The city of Mor is loosely detailed, whereas Lesserton is detailed to a level far beyond the typical home base in scope and depth.
That's an important point to understand about this product. The DM is being handed a toolkit to develop adventures in the ruined city of Mor, and a short sample adventure is provided. But Mor will require a fair amount of preparation by the DM to create additional adventures as the party explores. I'll put more notes below.
On the other hand, the home town, Lesserton, is extremely detailed. The town of 7,000+ is meant to be the home base for an ongoing campaign (as well as an adventure site of its own). In fact, 75% of the product page count is devoted to describing Lesserton and giving the players an introduction to the home town through the player's guide. This product, Lesserton and Mor, is a home town campaign setting, with a slice of ruins on the side. That being said, the town of Lesserton is extremely well done.
Lesserton is basically a swords & sorcery frontier town that embraces the tropes of D&D. The frontier economy is built on adventuring. There are opportunities to buy and sell magic items, carouse, train, get healing, perform research, and buy anything.
There are numerous subsystems in the Lesserton book to make adventures back in town interesting. There are simple systems for generating results when haggling, making bribes, carousing, gambling, and searching for love or adventure. In fact, most locations in the town have additional properties that provide modifiers to these activities. There are a handful of local gambling games (the giant centipede races are funny). Lesserton implements an idea tossed around on OSR blogs - earning experience by spending money, giving characters a reason to live large back in town.
The ruined city of Mor book provides a framework and toolkit. The ruined city is presented as a large hex crawl, and the DM is provided tables to generate hex contents (rubble, vegetation, ruined buildings, along with sub charts for building sizes, floors, and basements), and then plenty of random hazards and monsters to populate them. Four of the major factions of humanoids are given more detail, as is the various ways to approach and enter the city.
Two sample adventures are provided with the referees books, a murder mystery in the town, and a simple assault on a humanoid lair in the ruined city. The samples adventures really aren't the strength of this product.
I *loved* the town of Lesserton - if I don't use it, there would still be lots of ideas, subsystems, and rules to borrow. But I will find a way to work Lesserton into a campaign - it's well done enough to be used whole cloth and I think most players would have as much fun back in town as in the dungeon. What more could you ask for in a home base?
Mor is an interesting idea for a supplement - instead of a fully realized locale, it provides the DM a toolkit for generating adventure sites randomly. Is the OSR ready for such a product? I could certainly use some of the randomization ideas in the Black City. One creature I loved in Mor is called the Petromorph Queen - the mythic progenitor of all cloakers, mimics, piercers, and more. It's an excellent monster.
Overall, I'd give Lesserton and Mor a 4.5 out of 5 on the Beedometer.
I'd be hard pressed to recall a more detailed home base, or one with as many interesting things for the players to do back in town. My players would love all the carousing, gambling, and adventure seeking opportunities. I also haven't seen the approach to generating a sprawling ruins through random tables and hazards in a published work. The one issue is that this is an expensive product compared to a lot of other OSR products in the $4-7 range - I don't think that changes the rating, but folks will need to dig a little deeper beneath the seat cushions for loose change.