Squarespace is pretty. There's no debating that. It's gorgeous, even, and it lures people in with the promise of easy to use, friendly templates.
Wrong. The interface is unintuitive for the lay-user, and god forbid you customize even a bit of it -- customer support will drop you so fast, it'll leave your head spinning. I understand a reluctance to become involved in user-generated work... but isn't that the point of the platform? Take the templates (and that is what they are -- not live sites, not actionable work, but templates) and make them your own. It's not friendly. It's not user-driven. It's bad design.
And, moreover, let's all be honest with ourselves -- Squarespace is what Wix was three years ago. Overused, obviously templated, and ill-equipped for the various needs of its users. The premise was solid, but the execution, well. I want to say that it's lacking, but the reality is more akin to a black hole.