I've used a Freshette. IMO, more hassle than it's worth (I don't even know where mine is any more) - but I live in an area where there are a lot of woodlots and ditches (and cornfields between them, in season), and I'm not shy. Probably depends on your anatomy, but I've got a lot of soft tissue that got compressed by the funnel, and it just kind of made a mess, whereas if you just squat you can hold your labia out of the way. Plus then you've got to carry the p*ssy thing for the rest of your ride, and even possibly reuse it after it's been in your ziploc bag for hours. Ew.

My mom used the disposable paper ones before her knee replacement, when she felt the need to "hover" over public toilets but couldn't do it. She liked them a lot.

I might feel differently about it if I lived somewhere that didn't provide cover.