Service blueprints are less useful than wireframes but much more popular.
I can remember when UX was in the ascendancy and wireframes were highly-valued by clients (along with project plans). They created a sense of confidence in a proposed solution without being tarnished by the dirty business of actually delivering something.
Along came agile and the idea of “throwing design over the wall” became the hallmark of the waterfall practitioner. But that is exactly what we are doing now with service blueprints only we have convinced ourselves that the “strategicness” of them as a deliverable somehow means we are more enlightened.
Don’t believe the hype
Service blueprints are effective which convinces us of their value but this is not innate. Effective tools are always reified as somehow possessing magical properties.
There are as many bad service blueprints as there are bad wireframes. But bad service blueprints can do much more damage than bad wireframes, precisely because they are positioned as a much loftier work-shaping rather than work-defining deliverable.
Don’t mistake an argument for a specification
Just like a wireframe, a blueprint is a good visual argument. It’s power lies in the fact that it is convincing to different audiences. Use the power when you need it but move on.
Don’t confuse simplicity with complexity
A blueprint is a simplification.. No matter how much information it contains, it can never capture the whole mess. Don’t commit to documents over dealing with messy reality.