Disclosure: a friend of mine worked on art and design for this project. That's how it came to my attention.
The proliferation of fantasy gaming and narratives over the years have been a godsend to tabletop; it's easier to find and convert new players than it's ever been. But these new players are making the jump from big-budget fantasy films and videogames steeped that come steeped in the tropes of tabletop. They are wise before they ever sit down at the table, and in a lot of ways, they are harder than ever for new GMs to handle.
You've got to run a game with all the classic home-grown fantasy tropes players want...but none of the cliches and universe contrivances that hours of browsing TV Tropes and picking nits with guildies have taught them to spot and turn into punchlines.
The fantasy world and towns you build aren't compared to the mental pictures they composed reading Lord of the Rings in middle school. They're compared to Stormwind, Whiterun, and Peter Jackson's Laketown--vivid contexts rendered visually by thousands of artists at the top of their fields.
Most new players will want, in their hearts, a heroic narrative for their first campaign. But they've been trained to be cynical and opportunistic by fantasy gaming that don't marry mechanics with humanity, and the need to loot and grab and level up at all costs is not easy to suppress.
If I'm going to recommend a sourcebook for GMs running their first campaign, it'll need more than a hundred new proper nouns, a magic rehash, and the standard booster pack of redundant races and prestige classes. It'll need more than a premade adventure that hits the right beats and ends by writing a check for the GM to cash all on their own. It will need to offer the GM resources they can actually use: a world that feels right, fantasy that's classic yet grounded in history and internal logic, and lessons on how to bring out the inherent goodness in both player and nonplayer characters. I've never seen a sourcebook provide these with such precision and grace before Heroes of Thornwall.
This book is full of stuff, and precisely none of it is bullshit. It's not a worldbook that leaves an inexperienced GM to fill in the big fat Google Maps blanks on the fly; it makes a complete, detailed, and accessible resource of one town. Every page of this can provide a face-to-face scene, an emotional hook, or an answer to a player's gotcha question. This is a book you can use.
The starting adventure is pretty good. It's nothing fancy, but you probably don't want to get fancy on new players anyway. A good bit of thought has gone into making it feel grounded and providing the GM answers to players' fridge logic or genre savvy. To give an example: the adventure centers around hunting down and butchering goblins. I decided my character, a young priestess I styled as inexperienced and a touch naive, had decided that goblins were not congenitally evil but a victim of rough and ragged circumstances. It's a pretty well-worn trope, but it's one that's very plausible and one most fantasy publishers don't acknowledge--I've played way too many campaign starters that didn't put more than a fig leaf over the invasion and terrorism of another intelligent species. But what would have been an obnoxious and premise-stretching attitude in a WotC product was, in this adventure, the setup to a great scene--because it's difficult to argue nature and nurture when the newborn horrors of a goblin spawning pit are swarming to devour you alive, and it's difficult to be smug when your mace is covered in the brains of infants. Perversely, but memorably and successfully, Temple of Mordren justified our characters' heroism by having us kill babies. It couldn't have avoided the problem more deftly or naturally.
If you're looking for a Pathfinder sourcebook that provides a classic experience with modern grace and thoughtful design, look into this.