Strengths-

• encourages thinking by getting participants kinesthetically oriented (out of their normal paradigm)
• it's fun-it's hard to stay serious around legos
• it's a good stretch for most groups
• helps build a shared vision.

Weaknesses-

• for some situations, this is too far a stretch; appears childish to the analytically inclined
• may take too much time (relative to content generated) for shorter events
• may not work well if participants feel they're under a lot of pressure to resolve their events issues quickly

Specifications for success-

• again, it's the basics: prepare the participants for a Scan process; give them a strong assignment, worthy of their attention, ensure you've got a good mix of ideas (vantage points, agreement/disagreement) on each team; and set them to it.