There are different things that go by the name, but originally it was a martial art, yes. http://www.martialtaichi.co.uk/
Yeah Tai Chi use to be known as the MOST deadly martial art of all time, Yang Luchan (a founder of Tai Chi) was challenged by all the top martial artists in China and easily defeated them all and thus gained the title "Yang the Invincible" because no one could defeat him no matter what...something about using softness to overcome hardness, no force to overcome force, you know what they say "force binds the chi"...it is like spiritual martial arts...the greatest of all martial arts if mastered...in fact literally Tai Chi Chuan means "Supreme Boxing Art"... Remember Yang Lu'chan didn't just defeat all of his opponents, he did so effortlessly, without using force, like it was just nothing for him, with no struggle, and he was challenged by all the top, highest ranking martial artists in China...
taiji is great for your health, some people who practice taiji live active lives over the age of 100. it promotes great breathing and range of motion for your joints and body. your asking a question simular to "what good is yoga", both are very good for your body and promote health and fitness. also taijiquan is a martial arts form, if mastered with great practice it is very effective. you learn to manipulate the opponents strength while conserving your own energy. it is a soft style that was designed to counter hard styles. at advanced levels it is very demanding, watching somebody perform a set of slow movements is easy, but doing them yourself correctly is another thing. peace.
I tried it from a videotape I have. It looks simple, but man it's hard. I couldn't hold the pose for one second, never mind 15 minutes. I imagine it works incredibly well for strengthening your arms and legs, with low impact.
yeah totaly right, from afar it looks like a piece of cake. but some of the positional forms are fucking hard to hold. there are some serious low stances that kill your legs. its is perfect for training your core muscles, i love taiji especialy training outdoors on a nice day out in a park or a forest. or even by some kind of water like a river or a lake. the surroundings make it 100% better and more refreshing. peace.