Aikido is usually described as a non-aggressive martial art, which at first glance sounds a little contradictory. But in Aikido the emphasis is on control and restraint rather than inflicting injury upon your opponent or attacker. In practical terms this makes Aikido the only completely legal means of self-defence available in certain situations, for example hospital workers. In a hospital, situations can arise where a member of staff needs to defend themselves against an attacker but they are not allowed to do so by injuring that attacker. So other arts which might advocate strikes and throws as a means of defence would not necessarily be considered an appropriate means of defence. Kicking a violent patient in the head is not an appropriate action for a doctor to take, restraining them in a calm and effective manner is. This principle also extends to other professions where a similar situation may arise.
Often the best defence is simply to remain calm and not to panic. This is more often than not much more difficult than it sounds. In Aikido however there are practical exercises taught to increase awareness of tension in the body and increase the students ability to retain a calm mind even under pressure in difficult circumstances. As such much of the benefit of other practices such as yoga for example can be found within Aikido training, where they are effectively combined with practical self defence methods. Aikido is also unsurprisingly a good way to learn more about Japanese culture and history, and while Aikido as practiced in the western world is not the same as experiencing Japanese culture first hand in Japan itself (unless you are perhaps lucky enough to have a Japanese Aikido teacher), it is a good way to become more familiar with a special part of Japanese cultural heritage, namely its martial arts, or Budo as it is known in Japan.