The error reporting doesn't work properly (missing $self before call to checkProp in JSON/Schema.pm lines 309 and 317).
The boolean handling is broken. Firstly, the case checks value = 0 and value = 1 (always false). Second it assumes you are using a particular JSON parser, this breaks when you use JSON::XS which gives you a $value with ref 'JSON::XS::Boolean' not 'SCALAR'.
The link in the docs to RT goes to a non-existent queue (RT only has queues for non-developer release modules). I emailed the author with a patch to JSON/Schema.pm but didn't hear anything.