This is a very solid and well made lock, and has the weight to prove it. It should deter all but the most determined and well equipped thief. The problem I have is that it is too big to fit within my frame. I have a Specialized Allez 52cm frame and there is no way that the lock fits in the triangle, never nind with the EZmount. The shorter version would probably fit, but wouldn't allow attachment to as many solid objects.
In terms of security, I would thoroughly recommend this lock, but if you want to fit it to your bike, check the frame size first.