The Argyle Lorebook is one of the best campaign settings I've seen in a long time (back to the 1980's!) for any genre. The Land of Argyle is obviously a labour of love - a lot of work and passion has gone into this product, and it shows. The world setting is logical, the geopolitical situation is well thought out and magic takes a back seat. I haven't played in this world yet, but my feeling is that this low-magic campaign setting can lend itself to "neo old-school" play; that is players ask questions and use their wits, and the game master weaves the story instead of everyone relying on dice rolls.
Although the book is targeted at DnD/D20, it can be easily be adapted to any system. I intend to use it with QUERP by Greywood Publishing, along with Dungeon Crawl Classics: Saga of the Dragon Cult by Goodman Games to run a very simple hack 'n' slash campaign. However any adventure campaign that involves the player characters foiling the return of a great evil (especially if that evil wielded great magic or was undead) would work well in this campaign setting. Throw in the historical, political and economic tensions between the various races and city-states, and deep and complex roleplaying experience is possible as well.
If Silver Oak Studios can keep up the exceptional quality, I will eagerly look forward to more products. My only suggestion is to keep the current format of the campaign setting, which is relatively system neutral and/or easily modifiable.
[5 of 5 Stars!]