The problem I have with most setting blurbs is that 90% of them seem to say "this is a fantasy roleplaying game!!!!"
Example is Arcanis. I didn't feel that I knew why it was worth playing until I actually read through the book. It DOES have its own unique flavor.
Here is the blurb for their core book "Codex Arcanis":
The Shattered Empires Await!
Turmoil grips the lands of Onara. It is the end of an era and the dawn of a new age. It is an age of struggle against the end of existence; an age, which shall witness the rise of history's greatest champions. Will the world of Arcanis pass into Oblivion or will her heroes raise her up to new heights?
Mortals stumble in the darkness; Heroes light the way.
Be that Hero and Leave Your Mark Upon the Shattered Empires.
This is a really cool setting that I can't say enough good things about. But what does this blurb really tell us?
Ok, it's about a place that has "shattered" empires. That, and things are changing. But so what? What is actually happening? Is it grim and gritty as a result? What is play like?
This description I have chosen could also describe several other settings, and that is a problem. It doesn't tell me how this is unique, or even really whet my whistle. It's not even that it's badly written, it just doesn't give me the info I need to know. If I hadn't told you who the blurb was for, and you had played Arcanis, I still don't know if you'd recognize it. What about Eberron? The 5 nations and such, couldn't this same description fit there?
So, reading your blurb, I get that it has something to do with cities. That could have been accomplished with "Urbanis: fantasy city roleplaying."
What else makes Urbanis unique? I need to know:
1. Its flavor. What is the "feel" of the setting?
2. Its mechanical differences. Are there no more elves? Are there elemental powered factories?
3. Its genre. Ok, fantasy-ish. Is it high magic or low? Is it post apocalyptic, peak of an era of civilization, gritty, heroic, etc?
4. Why I should look into it further. What can I as a DM or Player do here that I can't do elsewhere? What is the fun that this has?
Maybe start with a very long description...describing it to us all...and then whittle it down to its core components?