It all depends on your goals...some people train for fitness, others self defense, confidence etc etc. it also depends on how much time you want/can devote to the training. I taught Krav Maga classes for a number of years, trained in Israel, Poland and the UK and for me, its main advantage is that (given quality instruction) it's easy to become reasonably proficient in months, rather than years as it relies on mainly natural reactions against threats/attacks. It's also about developing awareness of potential situations and building confidence.

The disadvantage is that it lends/takes from Muay Thai, mma, boxing etc and sometimes leaves students with a false sense of just how good they actually are. Some defenses against a well trained martial artist wouldn't work out well unless your Krav Maga was almost world class. That being said, the counter arguement is that your unlikely to run into a seasoned martial artist who is looking for a fight. Krav is certainly the most appropriate for anyone looking for an excellent standard of self defense against any Joe Public, no matter what size they are