We've got some at work (as well as lot of single sex). Those tend to be fine.
My experience with them in the evening is different.
One Prezzo I was in had a member of staff getting changed in one of the cubicals. He hadn't even bothered to lock the door. Nice.
Other times I've hated them include an event night with just two shared loos. They were absolutely destroyed by the end of the night. I had to apologise to the queue when DH didn't bother to lock the door properly so all the women and blokes were treated to a lovely sight. Grrrrr.
I tend to find the seats and floors are often wet. Sometimes I think it's because the crappy little sinks are too small and splash. Other times it's cos men miss.
I think generally multi sex loos are about companies saving money. They couldn't actually give a fuck about trans people. They just find it cheaper to install.
Once when I was on a train I opened the loo door to the charming sight of an old man pissing into the sink.
I always feel sorry for people with disabilities when I see the state their loos are sometimes left in.
One house I lived in had an outside loo (as well as inside) I used to send DH there. Sorted. Single sex loos are great.
Many toilet stories. The TRAs will rub their hands with glee. Don't care.