Give it a chance

The first lesson you have in tai chi chuan will be hindered by your own personality.
Even if you have trained tai chi chuan before, you are unlikely to see past the veil of your own self-consciousness and fears.

It is usually worth trying a few classes.
That way, you can settle-in a little and really observe what is taking place in class.
Pay particular attention to the more skilled students: what are they training? How adept do they seem? Are they having fun?