No feedback: Showing you is great, and you can go away and practice, but how do you know you are getting it right?
It's very subtle: However I describe Tai Chi techniques, will not be enough to convey what is required. I have tried - and by my own standards - have failed. The best way of learning is like I did - by going to a teacher who is prepared to place their hands on you and move you correctly. I have not known many teachers who actually do this.
Tai Chi should be differentiated for every student: Everyone finds different things easy and others difficult. When given feedback, each student should be assessed and the advice given to them should be prioritised and the most important lessons given first. When practicing on your own, it is easy to become obsessed by a particular aspect of the discipline and neglect what is really important.
If it looks good - doesn't mean it is: External impression can be very different from internal sense - Some of the most impressive fighters I have competed with have had forms that gave absolutely no hint of their skill. In fact some of them appeared to be very crude indeed. Although we all give clues, you only truly know how good someone is when you fight them.
The information age is fuelling a generation of armchair martial artists - people who have read the technical manuals, but have not done the work. Just pick a well-watched martial arts video on youtube, and you can read hundreds of small-minded comments from people who talk the talk and can't walk the walk. I have no wish to provide ammunition for these people.
If you really want to learn, come to my classes. Details are at http://www.richtaiji.co.uk