Interesting. I seem to get "Schema validation error" on anything with any slashes in it. I can enter just the hostname of my site but then I get a link going to the wrong place. (Not just because I'm lacking the path component -- it goes to something like https://www.lesserwrong.com/users/gjm/www.mccaughan.org.uk/ which is totally wrong.)
I thought that instead of everyone having to create a separate post for their first impressions, it would be more convenient to create a single post for this discussion. I'll post my own here soon.