We had out first big playtest. Our group consists of 6 people plus the GM (me).
We began by sharing our expectations for this adventure, we came up with:
Repression
Love
Vampire Hunting
Power Struggle
Fighting
Redemption
Intrigue

From that, I made an Antagonist, Baron Gilderoy. A Finishing School Master at a school where mysterious things were happening to the students.

  So, everyone made characters based on those concepts, we ended up with:
A Magical Healer
An aspiring actress who is in an arranged marriage with a man she doesn't love
A power hungry heir to a family fortune
Two Vampire Hunters

  The first scene was with a Vampire hunter and we were roaming the streets of London looking for signs of vampiric villainy. They were confronted by a bobby who was investigating a recent vampire attack. The players threw me for a loop and did not investigate further, but I went with the flow...

  The next scene was with Jen at the Finishing school, her character is getting ready to graduate, but her younger brother is just starting at the school. We met the Baron and he creeped her out.

  Next we had a scene where the Healer researched a new spell. She was looking for a way to detect the plague.

  Finally, our little Machiavelli went a calling on his grandfather, 3rd in line to inherit the rule of the family estate (he had already abdicated, but should something happen to his two sons, it would revert back to him). This was a cantankerous old man (84 years old) who was very used to getting what he wanted. He threatened to send his grandson to the war in South Africa to make a man out of him, but the conflict in the scene finally fell on setting up an arranged marriage with the female vampire hunter. We used the full-blown conflict rules and it was very tense and down to the wire. The players lost the conflict by one point and a message was sent to the Hunter's father requesting her hand in marriage.

  This group hasn't played many indie games, so there was a stutter start to get used to setting scenes and having more than the usual control over it all, but I feel it went well once they hit their stride. I, as the GM, still had a good amount of creative input and a decent workload. But I felt that the players were contributing to the story in a meaningful and collaborative way.

All,
  Well, we added two more players. and Inventor and a Politician.
  We did their scenes.
  Our Inventor made a steam-powered hang glider vehicle.
  Our Politician turned to a vampire

  Then it was my turn.
  I staged a vampire attack. But it wasn't by the Baron but by Du Loch. They hadn't met him before, but his intentions were clear. He was pouncing a servant girl carrying water.
  We broke into a conflict quick. I declared if I won I would feed on the girl. The players took various Intentions, including:
1) Save the girl
2) Earn fear and respect of Vampires
3) Character Advancements

  It was pretty interesting and the group conflict mechanics went alright. the one issue is, I squarely whooped the group again. During another playtest, a single NPC vs. multiple PCs were whomped pretty hard core.

  The difference was, that NPC did not use vampire powers.

  So, the fix is easy, we can give a special group bonus to non-vampires and deny that bonus from vampires.

  So, I would call it a GREAT playtest. And next week should be way more fun with what we know!