I feel compelled to share my own experience, since this question has been asked so often, but yet never properly answered.

Is Aikido an effective martial arts on its own?

Aikido was my first foray into martial arts or self-defense. Before Aikido, I had no prior experience, other than occasional scraps in school.

I learn Aikido for about two years straight, and thought I knew something about self-defense. Not expert, but something. And my illusion was broken when I took up Hapkido; which is a combination of korean TKD and Japanese Aikido. I froze during my first sparring match.

The truth is, Aikido on its own, is NOT an effective martial arts. Sure, you learn how to roll, how to apply locks, how to dodge punches and unbalance an opponent. But none of the stuff I learnt was ever applied in a sparring match, or under fighting conditions. Don't get too quick to say that if Aikido was applied in a sparring match, bones would get broken and wrists would be snapped. Hold your horses.

You learn in Aikido how to apply a lock. And if applied properly, it can be effective. I learnt that first hand. But the trick is, will you get the chance to apply the lock?

Were you taught in Aikido how to throw a proper punch? If not, you think you can dodge one? You have an idea how to counter punches, but have no clue about how to punch properly. Doesn't make sense to me.

You learn how to counter a kick, but have no real idea how to deliver a proper kick. I suppose that means you think you can catch a kick easily without getting your hands broken or ribs fractured.

You think you can take down an opponent in a real confrontation, but throughout your entire training, you have never sparred before in your life.

Have you ever experienced the fear of fighting a guy who weighs 30 pounds more than you?

Have you been in a confrontation where you have to move very fast to avoid a punch or a kick? Had you been in a sparring situation where the fight is over within 1-2 seconds?

You don't get all these lessons in an Aikido dojo. And as long as you had NEVER sparred before; boxed, wrestled or MMA, you don't know nuts about self-defense. It's like some dude saying that he's been learning how to swim on dry land.

Aikido as a martial arts, is effective. But it is effective ONLY as a complement to a martial arts that has taught you how to punch and kick and have regular sparring. Even O' Sensei started off his martial arts training NOT with Aikido, but with hard arts of spear fighting and Aiki-jujitsu.

There are a number of great Aikidokas in my dojo. And I noticed something that they all had in common; they all had years of training in other martial arts before coming to Aikido.

All other Aikidokas, including the dan grades, who did purely Aikido, are far behind. I had been hit (atemi) by a 2nd-Dan who did only Aikido. His atemi is weak, and wont even serve as an effective distraction. A good atemi should be sufficient to end the fight, and not merely serve as a distraction for you to pull off your Aikido lock.

If you want your Aikido to be effective, better start off with a martial arts that emphasises on kicking and striking, which are the most simple and common ways of fighting. Sparring is important.

I am still doing Aikido. And I learnt much more about my Aikido when I had to step into the ring to fight, than just merely attending an Aikido dojo.