  Yesterday, I had a class with one of my favourite teachers, she is not a regular teacher (that's why I could never remember her name), but every time she does a different class. We used the wall a lot in different poses, like the dog pose (Adho Mukha Svanasana), first with the hands on the wall and then turned around and put our heels on the wall. You feel the stretch differently and it doesn't mean that because you use the wall to help you it gets any easier. One posture that I feel very strange in is Uttanasana, having my back touching the wall, I get a feeling of dizziness and I lose my sense of direction. Then we moved to supta budha konasana with our backs at the wall and the heels as close to the body as possible, here again the wall keeps you 'honest' and erect.
I think using the wall just gives you an idea of how asanas are supposed to feel. It acts as a reminder that keeps you 'truthful' (you cannot cheat) to your practice. It's really very good to have different teachers and not just one or two, at the moment I have 5 and from each of them I get a different approach. I am just so sad that I will have to leave them so soon. 
