I only mucked around with it and liked what I saw. The built-in themes were decent-to-good. The "story" themes were excellent.
My only issue was I used the site to make a template for a Static Site Generator.
There is a button where you can export the site as html so you can deploy the site yourself.
Unfortunately the generated html/css/js was basically in a "obfuscated" form so it was hard to cut up the site into different partials etc used by all front-end templating engines.
When I asked for support, the support person was not a technical person so probably didn't understand what I wanted and what I meant. They just directed me to the instructions on how to export the site as html (which I already had done and mentioned).
That was unfortunate but I was only playing around so I didn't care enough to care.