A new feature of the new Android 4.0, a.k.a. Ice Cream Sandwich, has a new feature that will allow you to unlock the phone using facial recognition. Though if you prefer security over convenience you should try not to use this new feature.
As seen in a video created by a mobile blog, the face unlock feature can be fooled by showing it an image of the face used to set up the locking mechanism. You can do this by taking a picture with one phone and holding it up to another to try to fool the unlock feature.
A google representative has stated that it is considered a low security and experimental way of locking your phone and the interface warns users the face unlock is less secure than a pattern, pin, or password and that someone who looks similar to you could unlock your phone.
So this poses the question do I use this new feature because of the ease of use and the convenience even though it has been show that it has weakness and vulnerabilities. Good has said that they have started looking into the problem and that because Android 4.0 has not been released yet they are still working out the experimental system.