Yes, Aikido can be a very effective form of self-defence. However, it can take considerable time and effort before Aikido (or any martial art) can be used effectively in a self-defence situation.

The complex answer is "no" in the sense that I don't think anyone ever feels like they have "mastered" an art. If they do then they've stopped growing, or the art is too simple.

An old story might tell you some of the mindset you ought to apply when studying martial arts:

A young boy traveled across Japan to the school of a famous martial artist. When he arrived at the dojo he was given an audience by the sensei.

"What do you wish from me?" the master asked.

"I wish to be your student and become the finest karateka in the land," the boy replied. "How long must I study?"

"Ten years at least," the master answered.

"Ten years is a long time," said the boy. "What if I studied twice as hard as all your other students?"
"Twenty years," replied the master.

"Twenty years! What if I practice day and night with all my effort?"

"Thirty years," was the master's reply.

"How is it that each time I say I will work harder, you tell me that it will take longer?" the boy asked.

"The answer is clear. When one eye is fixed upon your destination, there is only one eye left with which to find the Way."

The answer to this question is very subjective - students of any particular martial art tend to favor that one over any other (otherwise they would probably be studying the other martial art).

There are many different but equally valid reasons for studying any martial art, such as for self defence, for spiritual growth or enlightenment, for general physical health, for self-confidence and more. Different martial arts, and even different styles within a particular martial art, emphasise different aspects.

Hence 'better' really depends on what it is you want out of a martial art. Even given this distinction, it is still a very subjective question so perhaps a better one would be 'Is Aikido better than any other martial art *for me*?'

This can only be answered by the individual asking the question.

An alternative way to answer this question is to simply say, 'No, Aikido is not 'better' or 'worse' than any other martial art. It is simply different.'

Your training is your own responsibility. No one is going to take you by the hand and lead you to proficiency in aikido. In particular, it is not the responsibility of the instructor or senior students to see to it that you learn anything. Part of aikido training is learning to observe effectively. Before asking for help, therefore, you should first try to figure the technique out for yourself by watching others.

Aikido training encompasses more than techniques. Training in aikido includes observation and modification of both physical and psychological patterns of thought and behavior. In particular, you must pay attention to the way you react to various sorts of circumstances. Thus part of aikido training is the cultivation of (self-)awareness.

The following point is very important: Aikido training is a cooperative, not competitive, enterprise. Techniques are learned through training with a partner, not an opponent. You must always be careful to practice in such a way that you temper the speed and power of your technique in accordance with the abilities of your partner. Your partner is lending his/her body to you for you to practice on -- it is not unreasonable to expect you to take good care of what has been lent you.

Aikido training may sometimes be very frustrating. Learning to cope with this frustration is also a part of aikido training. Practitioners need to observe themselves in order to determine the root of their frustration and dissatisfaction with their progress. Sometimes the cause is a tendency to compare oneself too closely with other trainees. Notice, however, that this is itself a form of competition. It is a fine thing to admire the talents of others and to strive to emulate them, but care should be taken not to allow comparisons with others to foster resentment, or excessive self-criticism.

If at any time during aikido training you become too tired to continue or if an injury prevents you from performing some aikido movement or technique, it is permissible to bow out of practice temporarily until you feel able to continue. If you must leave the mat, ask the instructor for permission.

Third, aikido techniques often take a while to learn to perform correctly. Ask your partner to offer less resistance until you have learned to perform the technique a little better.

Fourth, many aikido techniques cannot be performed effectively without the concomitant application of atemi (a strike delivered to the attacker for the purpose of facilitating the subsequent application of the technique). For safety's sake, atemi is often omitted during practice. Again, ask for your partner's cooperation.

Classically, those arts which claim to provide a transformative framework for their practitioners are rooted in religious and philosophical traditions such as Buddhism and Taoism (the influence of Shinto on Japanese arts is usually comparatively small). In Japan, Zen Buddhism exercised the strongest influence on the development of transformative arts. Although Morihei Ueshiba was far less influenced by Taoism and Zen than by the "new religion," Omotokyo, it is certainly possible to incorporate aspects of Zen and Taoist philosophy and practice into aikido. Moreover, Omotokyo is largely rooted in a complex structure of neo-shinto mystical concepts and beliefs. It would be wildly implausible to suppose that adoption of this structure is a necessary condition for psycho-physical transformation through aikido.

So far as the incorporation of Zen and Taoist practices and philosophies into aikido is concerned, psycho-physical transformation through the practice of aikido will be little different from psycho-physical transformation through the practice of arts such as karate, kyudo, and tea ceremony. All these arts have in common the goal of instilling in their practitioners cognitive equanimity, spontaneity of action/response, and receptivity to the character of things just as they are (shinnyo). The primary means for producing these sorts of dispositions in trainees is a two-fold focus on repetition of the fundamental movements and positions of the art, and on preserving mindfulness in practice.

The fact that aikido training is always cooperative provides another focus for construing personal transformation through aikido. Cooperative training facilitates the abandonment of a competitive mind-set which reinforces the perception of self-other dichotomies. Cooperative training also instills a regard for the safety and well-being of one's partner. This attitude of concern for others is then to be extended to other situations than the practice of aikido. In other words, the cooperative framework for aikido practice is supposed to translate directly into a framework for ethical behavior is one's daily life.

Talk to various students and ask their opinions meanwhile noting their demeanor. A good sign is if either before or after a class which you are observing, a senior student or instructor comes over and talks to you. If you are ignored, it may not be the kind of dojo you are looking for.

Remember, this is where you hope to be spending a fair amount of time, and you want it to be a positive and rewarding experience. One final question, also very important, is simply "Do I like this dojo and these people?"

Beware of any dojo that tries to pressure you into a quick decision or is averse to letting you watch a few classes.

While the chief instructor's rank may be somewhat important, be wary of inflated qualifications. Although an affiliation with a national or international organization is no guarantee of quality (and some teachers are not affiliated at all), it can be a useful indication. Promotions given by non-affiliated dojos are not likely to be recognized anywhere else, and this may well be a consideration.