While passwords can be brute forced given enough time, your face is almost certainly available to someone who has access to get at your computer.
Also, you could say that face recognition is just as secure as writing a reasonably long password on your forehead. Someone takes a picture and boom. Access.
Personally, I refrain from writing my passwords on my forehead - regardless if I can see a suspicious-looking character taking a picture of me square-enough in the face to capture all the digits. And, I also refrain of using or buying face recognition devices...