I have used it in the past. I feel that it’s more user friendly than many of the others. You have the option to message someone at the same time that you like them. You can see the likes that you get so you have the option to match immediately if you’re interested. As far as I know, there is no paid version.
I’d personally not worry about the yellowing. I’d say clean it up to remove actual dirt and scuffs and don’t worry about the discoloration. Yellowed electronics are peak retro. Hook it up to an old yellowed CRT monitor.