I've heard a few reports of guys who quit T and said that their voices lost a little something, but I don't know how true those reports are. You might be able to find out more if you hunt around on YouTube.
If you are young enough when you start T, you should have some skeletal changes. Those won't revert.
Your junk will grow, and that shouldn't change. But if your sex drive ramped up while you were on T, it should go back down when you stop.
If you were fertile when you started T, you should start bleeding again when you quit unless you were on the verge of menopause when you started. This means that you can get pregnant and be another Thomas Beatie.
There are other reported effects (diminished sense of smell for some guys and more visual orientation), and I don't know if they revert. T works changes in the brain. Some could be permanent.
Don't forget the psychological effects. I feel much better about myself on T, but that could be psychosomatic.