These knives are every where. That was the an earlier lock mechanism, currently called the slide-lock. It's still available on some knives, including the new Cheese Knife that was just released last year.
Testing I guess showed it was maybe not strong enough for rescue workers, and the new liner-lock models are reported to be much stronger. However for most practical purposes it is fine, I don't do things that abuse or put undo force on the lock, I use the knives as if they have no lock, and am glad the safety feature is there if I make a mistake.
I don't think I've heard of anyone having any real problem with this lock, but it might be harder to keep clean if you use the knife in certain environments.
Give us more information on why you're asking, and your specific usage, and concerns.