I don’t think they are too common and to be honest I’m not sure how comfortable they’d be for the woman.
As Charlee says they are great if you’re doing a duo and don’t want to switch condoms every time! I’ve only had that experience once and it felt like I was a porn star. Being able to go from woman to woman without any interruptions is incredible
Without wanting to sound too crude or rude, depending on how big you are, and how tight she is, I’d think they could be either wonderful or disappointing.