I trained in Krav for awhile at the S.F school, it seems to really vary instructor by instructor more than any other MA I have studied. I had a couple of LEO's as instructors who were excellent and some others who werent. Also the american schools seemed, at the time I was there at least, to keep expanding the curriculum, adding things like spinning back kicks, highly impractical and padding the lessons for no other reason than to keep students and issuing ranks. The true Krav system is brutally simple in its practice.

When ever I'm forming my opinion of a self defence system I first look at the way they handle weapons, particularly knives and then work back from there, and what I've found is that there are just way... too many holes in thier principles. But first let me say that I appreciate the way they try to super simplifly violence for the average joe giving them a couple of targets on the human body that are readily injured and some different ways of getting it done.
But my biggest problem is still with the way Krav amoung others handle weapons, Any system that still teaches you to go after the tool in the guy's hand instead of trying to shut the man off is in my opinion living in the stone age. There is one principle in Krav that I could really appreciate and it was "Blasting"(hope I got it right) which basically looked like in it's simplist form throwing yourself into and through the man while picking a target, and I believed it is used for when you are caught by surprised(please correct me if I'm wrong), and I was happy to see that when the guy demonstrated it he showed no focus on what the man was trying to do but rather his focus was on what he wanted to do to the man, and I sat and wondered and said "gee' why don't they do that for all thier techniques? why is the focus always on what the other guy is doing rather than what you want to do to the man?
To me it's like if it's already universally agreed that in a situation involving a knife whether you are the one holding the knife or being attacked you will probably get cut, then why not risk getting that one cut on your way to lets say hitting him on the side of the neck or throat as opposed to wrestling over an object that can only hurt you if the man has an active brain? and the same effort i used to grab his hand could have been used to shut him off instead. It's like if I punch a guy in the throat and then put a knife in his hand, can he then hurt me because he has the knife in his hands? but to each his own