The techniques in Krav are, for the most part, good, basic, and effective.
Once again, if you want to see what they are, just click here:
Krav Maga DFW Curriculum Main Page
Whether or not someone can effectively use these techniques is an ENTIRELY different question. That is completely dependent on the instructor's competency and the student's dedication to training.
My guess is that a lot of Krav schools have instructors who haven't mastered the skills they are trying to teach and students who aren't training intensively.
There's no quick fix. To learn to strike and defend effectively in any fighting system/MA, you need to train extensively under good instructors.
The reason that Krav is taught to Israeli military recruits is that it's a decent way of quickly learning some RUDIMENTARY self-defense techniques. This may give the recruits some advantage over the average person on the street who has had no training. How would someone who has trained Krav for a few weeks fare in a self-defense encounter against someone who has trained extensively in boxing/MT/BJJ/Judo/etc.? Poorly.
How would someone who has trained Krav intensively for several years with good instructors fare in a self-defense encounter against someone with no fight training? I think the Krav practitioner would have a significant advantage.
How would someone who has trained Krav intensively for several years with good instructors fare in a self-defense encounter against someone who has trained extensively in boxing/MT/BJJ/Judo/etc.? Hard to say...