It would be interesting to see a "When structural-typing is better than prismatic/schema" section in the readme. I read the readme, and I don't see why you can't use something like s/validate instead of built-like. So instead of:

    (type! :Point (requires :x :y))
    (some->> points
         (all-built-like :Point)
         (map color)
         (map embellish))

To keep it simple, as in the first example of the whirlwind tour, we could use:

    (def Point {:x s/Any :y s/Any})
    (some->> points
         (s/validate [Point])
         (map color)
         (map embellish))

It's good that structural-typing does not use macros, instead building ontop of specter which is pretty cool. So is there a performance enhancement?

It's clear that one should use structural-typing where an expertise with specter has been attained, Not sure when else it's the best choice.