I would say they're great until they aren't. Which means at some point in a session or in a long-lived-project they will resist very hard being steered like it would be done by another developer, product manager, a designer, or just the market in general.
Most people don't find this to happen because the size of projects and the granularity of the expectations are wildly different.
Most people don't find this to happen because the size of projects and the granularity of the expectations are wildly different.