I do it regularly. I've been a longtime back pain sufferer it helps a ton.
I've got some back injuries (disc related) and was recently recommended that I give yoga a try to work on core strengthening and flexibility. However, I'm just concerned about some of the movements being more stressful on the back. When you started, did you start with individual lessons/classes and did the instructor work with you to modify the program/stretches/poses so as to not do certain movements that would further hurt the back?