Saw this type of lock on mythbusters and it was easily defeated!!
The fact here bandook is that all door access points have some level of vulnerability. The level of sy provided by this door lock is no different to a standard door lock.
When I moved in to this house the front door had a 5 lever mortice, the highest rated door lock as preferred by insurers. This door was not locked when it was closed but relied on the action of turning a key inside. When a key was on the inside someone else with another key could not gain access as there was only room in the lock for one key at any one time.
My point?
The point here is that there is more to door/ access sy than merely the lock. It is a procedural factor that enhances security and not solely the mechanism employed. If my wife was alone in the house and the door bell rang, she would answer the door (after looking through the door (peephole). After opening the door the unknown could easily push the door resulting in a too-ing and fro-ing. My wife would then have to push the door closed and then to turn a key to lock it - that is if there was a key in it in the first place.
Many UPVC front doors have the same lock mechanism as mine. You close the door, it is locked. With mine however, it provides ease of function and increased sy through procedure. No keys can be lost (by the kids) and any person can gain entry if we supply them the numeric code.
People these days do not pick locks. If a window or door is not already open then they will go round the back of the house and prise them open or cut the glass.
Security is defence in depth and not only the door lock. My house has body heat and motion detectors around the entire property that provides an audible alert. I have CCTV that will send me an image to my BlackBerry when it detects motion. All these methods provide an early warning of trespass before anyone even approaches the door. Don't ask me what would happen if someone actually managed to gain access.
There are door locks and there are door locks. Some are better than others but whatever one you choose must be balanced in relation to the threat and in balance with other systems employed.
Rich H