We've long believed personas were a valuable design tool. We were initially disheartened by the many failures we'd seen, but now that we've had a chance to study some successes in-depth, we can see teams realizing the promised benefits.
The trick is to not rush into it. Ensuring the organization is at the right place in their user experience maturity is critical. Using a jump-start technique works, but the team needs to follow up with robust research. Finally, keeping the personas alive through frequent discussions, especially around key decisions and trade-off conversations, makes them a valuable design asset.
The Essence of a Successful Persona Project - article by Jared Spool