First time going to My Thai today. My lunch was okay -- nothing spectacular. I was hoping to bring leftovers home for dinner, but the lunch portion is pretty small. In addition, the "salad" is basically a few pieces of lettuce, a slice of cucumber, and a half-slice of tomato. It's TINY. So just don't count on that providing any satiation. In terms of portion, I'd go to Peking Garden (not Thai, I know) over My Thai.
I did try my friends' lunches (which were off the full menu), and they were much better. Don't know if it's just a dedicated lunch menu thing, but when I go back (which I will because I love Thai and don't want to have to drive across town to get it), I'll order off the full menu.