My impression of declarative programming is that it looks good in the "Hello, world" and other basic examples because you don't have to dip into the escape hatches. But when presented with real-world problems, you end up spending more time trying to get their framework to do what you want through the escape hatches than if you had just written your own program using a normal programming language and a well-designed library.
Something like Django or Rails, is no longer just a "declarative library" it's a framework. You're using their patterns, and you're limited to their escape hatches.
