I have been studying KM since September 07. Not very long and my first introduction to any form of MA (though at my school we're very adamant about not calling KM an art).
I love KM and encourage everyone I talk with to try it out. Keep in mind that like all MA schools, YMMV in regards to quality.
That's the beauty of Krav, it's simple to pick up. We don't start actually sparring until Level 2, some schools may be different though. Roughness wise, for the first few weeks you will probably feel like a train has run you over if you aren't relatively fit. At my school, they work you like crazy.
Best advice would be to go watch a class or two, talk with the Instructors and then decide for yourself.