There's barely anyone on it here. And all girls on Feeld also have a Tinder account btw.
One of the girls who was very briefly on my harem (I forgot the nickname I gave her in my log) had an account on Feeld and got flooded with matches but I met her on Tinder anyway and didn't find her on Feeld.
I'm assuming the male/female ratio on kink stuff like Feeld is even worse than on Tinder. If you're not part of a couple and looking to swing, you're going to be fighting an uphill battle.
But my greatest issue is just the crowd it attracts. Like pancakemouse said, it's full of those poly/bdsm/kink people who suck all the fun out of social interactions. Every single one of them also lists "philosophy" and "literature" as an interest and they want to make everything an essay-writing contest. I get that they need to screen out the low quality dickpic-sending guys on there but god damn that crowd is so full of themselves. They're not fun to talk to at all. All the girls are into that pseudo-intellectual stuff.
Anyway, I'm probably biased, but the OK Cupid crowd is the same as well (but at least I've scored two lays on OKC before their site went to shit.)