This is a new thing offered by my employer. We don't pay anything, I don't know what the employer pays, but I'd guess it can't be a lot (school trust).
I've just been paid my first claim, for physio I was having anyway. It has fairly low maximus (unless you upgrade), but i reckon in a year I'll claim c. £350 just for dentist, opticians, physio and prescription charges i would have been paying anyway. Then there's an option for counselling and some alternative therapies if you want them, and an online GP, gym membership discount, shopping offers.
So how do the insurers make any money, if everyone will legitimately be able to claim up to the maximum, just through routine treatments?