I know that it's easy to write Krav Maga off as an over-commercialized self defense based aerobic workout, but I'd encourage people that are interested in picking up a martial art to reconsider before they decide something like that.
The KM school that I go to has been really great so far. One of the instructors specializes more in striking than in grappling, and has a pretty solid traditional MA background, in addition to years of training and teaching Krav. The other instructor specializes in grappling with a Brazilian jiu-jitsu base, and he's the hand to hand combat instructor for the Police Department for the county that I live in. Both are fluid, competent strikers and grapplers with a knack for teaching and a genuine interest in helping people learn to fight and defend themselves.
While it is true that Krav Maga does put an intense emphasis on fast, explosive bursts of chained attacks to finish fights, and does emphasize strikes that may not be legal in competition, I think that it's easy to argue that a fighter with a striking base in KM could make a transition to competitive fighting and do reasonably well. At the school that I attend, we learn and refine punches, kicks, knees, and elbows, and because KM is a hybrid art, we see attacks from a variety of sources (Karate style front kicks, Thai style leg kicks, Judo style throws, etc).
Sorry that I've been so long winded, I just want to make it clear that while there are some Krav schools that fall into the McDojo aerobic fitness category, this is by no means true for all of them.