After the simulation/role play, we asked participants to write up the
good, the bad and the puzzles of the method they had practiced. The
group that used user stories only identified the following:

GOOD
====

- positive message [to the customer]
- simple

BAD
===

- low customer involvement
- no focus on problem [of eliciting and planning non-functional requirements]

PUZZLES
=======

- when to start with NFR
- [can you busy yourself an] entire iteration with only NFR?


I added the clarifications between []s.

Here is the output from the group that complemented user stories with
explicit nightmare scenario's.

GOOD
====

- brings bad things out in the open
- makes it quantifiable: nightmares

BAD
===

- overcomplicates the planning game
- too much focus on the 'negative'
- it's hard to track the correlation between dream and nightmare

PUZZLE
======

- when is a nightmare not just part of a dream
- relation between NFR and nightmare