Well, Vova, its like this. At least, in my world, its like this. I did Aikido for a few months with an girlfriend at the time. I enjoyed it, very much. Now, for its usefullness in everyday situations, its okay. Most guys are going to be the haymaker throwing type. Which is perfect for an Aikido-ka. But if you ever come up against the guy who knows how to jab, cross, hook, and stick and move, you better have a plan. As Hock has said, either in the forum or his blog, a boxer doesn't give an Aikido-ka enough energy to work with, unless maybe your Morihei Ueshiba himself. There is nothing that says you can't practice Aikido primarily. Just remember, you have to have a plan for when the bad guy isn't fighting how you want him to. In addition to all that, I really like the spiritual side of Aikido, and the idea of trying not to hurt the bad guy as much as possible. Now, if he keeps coming for more, then you dish out more. But, the principles of blending and entering are two of the biggest things that I took away from my Aikido practice.
In summation, I feel that Aikido is only as practical as the amount of time you put into practicing both it, AND your backup plan. As to whether or not it works, everything works, if you apply the right amount of hammerfist strikes.
Kent