Love them. I have similar from Miss Selfridge (a tenner in the sale!) and I wear with everything including skirts.
Agree with Nilbyname to an extent but WRT to Boden skirts - I think it depends on the length. Most Boden a-line skirts are a hideously frumpy length. However, I have a daisy print version from about 10 years ago which I lopped about 3 inches off the hem so it sits an inch above my knee. The sandals look great with it. Ditto the A-line linen dress from last year which also sits above the knee on me.
Having said all of that, I do think some women can rock those sandals with an on the knee or below the knee skirt and look incredibly cool in a Stella MacCartney-esque way. A gentle nod to 70s summer chic.