Been very happy with Squarespace so far, I’ve stuck with it longer than any other blog platform I have played with over the years.
My one major complaint: SSL login is not available for the basic-level plan
That is the one feature I would like to see added to the basic plan. This makes it a bit of a headache if I want to login when I’m out and about on public wifi. Then I have to either login using the app on my phone over 3G(err, I mean “4G”) or use logmein to remote to a computer at my house and make a post. Not an ideal setup.
Beyond that I have no complaints, Squarespace rocks, though a bit insecurely for some plans.