Garbage - absolute garbage. I spend so much time getting it right, and then my site changes. Things just disappear. And when I send screenshots to customer support of before and after (it's happened multiple times, so I started screeningshotting right after I made the edit and then a few days later), they just send me links to how to use the editor. Things are literally shifting and disappearing on my page, and somehow it's not their problem - it's mine. Seriously considering leaving Squarespace.
@ShaneGardner I asked customer service if I could revert and they said no. Luckily, I only "upgraded" one page. They did tell me I could recreate the page with the old editor, but when I went to do it, it defaulted to the fluid editor. So I'm stuck with one of my most important pages being something I can't rely on... I have to check it regularly to see if the content has shifted around or deleted itself.