Using Crux's Datalog query language from Clojure is great. Normally if your query building library is giving you a data-like interface, then you're relying on some abstraction that will inevitably leak in places (and let's not talk about ORMs), but since Crux really does natively use EDN (Clojure's data syntax, roughly analogous to JSON) for its query language, you've eliminated an entire layer of complexity in your application, and you also have the entire programming language at your disposal for compositionally building queries.
That's not to say that using the SQL API is a bad idea, but if you're using Crux from Clojure, you'd be missing out on some stuff.
That's not to say that using the SQL API is a bad idea, but if you're using Crux from Clojure, you'd be missing out on some stuff.