Overall a very cool "micro-setting." I can easily see running entire stories just in the city and guild as they are presented here.
The additional character options really give a lot of good flavor to building a group of thieves that would be hard to accomplish just using the core SWD rules. The Hindrances are great, and most of the Edges are pretty sweet as well (with a few exceptions detailed below).
Likewise, the Minions section gives you a more detailed framework for creating allies for your characters (something granted by various Edges in the setting), and is a great addition to the SWD Ally rules in this or any setting.
The setting itself is super detailed and will make it easy to write and run lots of thief-ly adventures. The art and maps are great, and help flesh the ideas presented out very well.
That said, there are a few things that jumped out as needing improvement or just not quite "there," and I'll go over them below. However, the takeaway I want to give is that this is definitely worth picking up if you want to run a campaign centered on a thieves' guild or even if you just have a thief in your fantasy(ish) games and need a guild for them to belong to. The guild could also be a great "enemy faction" in a game. Super cool stuff.
Now, on with the nit-picking! (likely of more interest to the designer than the average reader/user, but you might find my "gripes" useful)
- Typos and missing punctuation.
Page 3, A Note About Race heading
missing period at end of last sentence "...feel free to create an elf character"
Page 5, Hinderances [sic] header
misspelled, should be Hindrances
The perspective of the Edges jumps around a lot. The switch from first to second to third is somewhat clunky, in my opinion.
A couple of the combat related edges stray away from Fast, Furious, and Fun, adding a lot of minutely detailed "if-then" conditions to various aspects of combat. This isn't necessarily bad if you want a little more crunch, but it could slow things down somewhat. For example, see the Mobile Defense edge. It feels a little more like d20 style play than SW to me with its conditions and various bonus states depending on them.
The Document Forger professional edge requires the input of 3 Attribute points and at least 4 skill points as well as taking up an Edge, but gives you no bonuses to forging documents (which is handled with the Repair skill per the setting). Rather, it gives penalties to the Notice roll of the viewer of the document to recognize it as fake if they are "unfamiliar with the type of document" or "only glance at it." How often are you bothering to forge a document just to show it to someone that isn't familiar with it or won't bother looking at it? Most professional Edges grant bonuses to the character for performing an action. This Edge is just convoluted in its current form, and doesn't seem to grant much for the amount of character building resources it requires.
The Forgettable Face background edge is a good idea, but is marred by its wording. It gives a +2 bonus to all rolls related to disguise. Okay, cool. But it also gives a +2 bonus on all rolls related to being recognized...wait. Huh? It works if you assume that the meaning is "inflicts a -2 penalty to Notice rolls to recognize the character," but that's not explicitly stated. The wording could use some cleanup.
This whole section is rife with small formatting issues that, while they could be argued as merely stylistic choices, just don't present the material as well as they could. For example, although all of the important Wild Card NPCs are appropriately marked with the guild symbol, their names are just in the same font as the rest of the text and underlined. In most other supplements and settings, key NPCs are much more loudly announced.
Likewise the names of locations. Just a simple underline, with headers in the same font but larger. It leaves me with the feeling that I'm reading a Word document with art scattered in rather than a fully designed book.
As another example, there is a really sudden and poorly "called out" jump from notable guild figures to guild services that doesn't suit the change in the material's focus. Small header, no spacing to differentiate the sections, just straight from a NPC's stats to guild services all the sudden at the bottom of pg 31. Could use a much larger header and some space.
So yeah. Design aesthetics and a few rules quibbles aside, the whole setting is really cool and I can't wait to get some mileage out of it!