Ju-Jutsu is one the most versatile martial arts. This is due to its history: although the name suggests otherwise, Ju-Jutsu (spelled this way, and pronounced yu-yutsu) was developed in Germany in the late 1960s, comissioned by the Ministy of the Interior as a self-defense system for the police, border patrol and other units.
The developers (the Deutsche Dan-Kollegium) drew heavily from the Asian martial arts that were taught then: Judo, Karate, Aikido. Later other elements from boxing, wrestling, and others were added. The result is very eclectic: the belt test curriculum includes punches, kicks, elbow techniques, a slightly reduced set of throws and ground fighting techniques from Judo, wrist locks, foot locks, pressure points - the whole spectrum of meanness.
The nae Ju-Jutsu was of course chosen as a reference to Jiu-Jitsu, the traditional unarmed combat arts of the Samurai. Since Jiu-Jitsu is a catch-all name for a variery of schools and disciplines as well, the name Ju-Jutsu is reasonable.
Ju-Jutsu has two main areas of interest: self-defense and competition. In competition, all ranges (striking, throws, and groundwork) are used, and apart from full contact punches and kicks, a wide variety of techniques is allowed. In self-defense, reasonable combinations of techniques against various pre-determined attacks are devised and practiced. Here, techniques can be useful that do not often occur in sparring.
Ju-jutsu's versatility is both its greatest advantage and the greatest potential flaw, compared to other martial arts: many things are practiced, but hardly anything intensely enough to really perfect it. Hence Ju-Jutsu is a good style for martial artists who have a good base in a more narrow disciple and want to fill the gaps; as a stand-alone style, it requires a lot of dedication to become good.