Had zero problems pairing - running win10 with some knockoff ultra slim USB bluetooth adapter. I really like this keyboard. Ordered mine with gateron clears - incredibly sensitive.
SkylinedUpdate as I look back at old comments - I am juuuust about to replace this with the CTRL from Massdrop. It still works fine - although it was dropping connectivity intermittently until I upgraded my motherboard to something with onboard bluetooth. It did not like the dongle or Gigabyte bluetooth card I was using for about three years when I went through a BT driver upgrade, but since updating my mobo all is fine. It still holds a battery charge for about a week or about 3-4hours a day use without issue. Still a solid board for the price and I'll probably bring it to work.