Krav maga's popularity is exploding around the world as martial artists and those interested in self defense see the real value in its simplicity and its military credentials.
But no system is perfect or 100% reliable and there is a serious danger that krav maga's flaws are being overlooked. This leads to complacency and over-confidence, which will put Krav Maga students in real danger in a real self-defense situation.
Two important flaws in krav maga are:
1) a lack of attention to the importance of power in techniques
Krav maga was developed for commandos - elite special forces soldiers. These are strong, healthy, aggressive men who can deliver strength and power. Unfortunately many students are not so tough and no amount of new techniques learned will change that. There is no magic strike in the martial arts: you have to deliver significant force to do damage and the majority of krav maga students I see cannot do that, especially in striking techniques. Take a look at these typical examples of the style and focus your attention on the amount of force they are using - particularly in the striking techniques and above all punches, kicks and hammer-fist strikes. Ask yourself honestly - how much damage would that amount of power do?
The techniques are physically sound and simple - but against a strong, aggressive opponent they would lack the necessary stopping power. Like many of the traditional martial arts, in which sparring is practiced without contact, the krav maga student develops the dangerous habit of striking gently in training. And in the street it is all about habit - you don't have time to think and will go into autopilot. There is also the ancient problem of opponent compliance - and this applies more to holds and throws. If the opponent is not your friend it really isn't going to be as easy as it is in the gym. It's no use pretending that your techniques will develop additional power when you are tired and frightened and in pain - the opposite is true. If you have ever tried boxing or thai boxing then you will know the frustration you feel when your best techniques seem to have little effect on your opponent due to his skill and your fatigue. In the street this could mean death.
The solution to this problem is to practice full contact krav maga to expose and address these weaknesses. Alternatively students should develop power using a punch bag and with other full contact styles - ideally muay thai (thai boxing) which has always been full contact and is possibly the best single style for self defense in the world (although no system is perfect and muai thai lacks, for example, essential self defense pressure points training).
2) The military-scenario hangover
In the extremely unlikely event that you're behind enemy lines and one guy points a gun at you and there are no other options then krav maga's disarming techniques might just work. They are physically efficient and simple. However you are far more likely to get shot if you try them. And in the real world attackers come in gangs of at least two. If they point a knife or a gun at you then they want something - give it to them! If they want you dead then you will never see the knife and you may not see the gun - you may never know what hit you. Krav maga's focus on disarming a single knifeman or gunman are dangerously unrealistic. This creates dangerous and mistaken overconfidence - and a mistaken impression that there are simple solutions or responses to being attacked with a knife or a gun. There are none and you can expect to get hurt if that is what the attacker really intends to achieve.
Your best option, I repeat, is to do what they ask or try to escape if possible. Do not fight with an armed man unless he is actively trying to kill you right now. It is almost infinitely likely that he will win the fight, no matter how good you may be. Ask your krav maga instructor - especially if he is ex-special forces. He will tell you the same thing and you need to maintain a keen awareness of the fact.
To summarise, my advice is to compliment your krav maga training with full contact training (ideally muay thai) and heavy bag work to develop maximum power and realism. Throughout your training you should maintain an awareness of pressure points and their effects because hitting where it counts will make all the difference. This information can be learned here:
Self Defense Pressure Points DVD