Roleplayers Chronicle have done an extensive review of Quintessence (no spoilers).
“Quintessence is fantastic! It contains a great, involved storyline, lots of opportunities for different methods of game-play, and you get to play on the moon! When you dig into the mechanics surrounding the moon adventure, its not only interesting, but so fantastical that everything becomes that much more enjoyable because the possibilities are virtually endless!”
http://roleplayerschronicle.com/?p=7704
This month’s Signs & Portents has an excerpt from Quintessence – giving details of London in the Clockwork & Chivalry world. It’s a