Atmas

Alhough it is generally not a great idea to tout one's experience in martial arts (it gives rise to chips on shoulders and all sorts of challenges and ridiculous hootenanny), I have trained in and studied martial arts in several disciplines for several decades. My training has largely focused on Korean styles though some of them bear striking resemblance to certain Japanese disciplines.
And yes, I have studied tai chi chuan for some years. The beauty of tai chi (and baguazhang and the other so-called "internal" styles) is that it really is a form of moving meditation. Alternative health practitioners tout its ability to help lower blood pressure almost without effort.
And it is a martial art. But be careful: you won't be jumping about and kicking through bricks with it. The actual martial aspects reveal themselves very, very gradually and so for self defense it is a rather poor choice if you're seeking immediate benefit.
But if you stay with it and practice for a sufficient period, you will understand why great tai chi masters are considered indomitable. But a sufficient period is often thought to be 15 to 20 years, far longer than most martial arts.

For several years I studied a martial art called iaito, which is the art of drawing the Japanese sword from the scabbard and attacking the opponent in one motion. I desired a highly refined enterprise that involved mental concentration and physical precision, but with no real applicable self-defense aspects. It certainly provided that.