I eat at Tom Yum at least once a week. I do it because of the food. Sure, their service can be bad and slow. It's normally when they are very crowded or understaffed. It's rare to come in here at 12noon and get a table. Most of the time, the seats are filled. Really, the slow service does not bother me. They are always nice, I've never seen them be rude. They may take your order fast and move on in, but that's during the lunch rush.
Anyway, back to the food. Their soup they give you as a starter (it's free) is delicious. I always gobble it up. I love the following: Tom Yum soup, broccoli noodle, pad thai, yellow curry, massaman curry, thai fried rice, and sweet potato appetizer. The broccoli and eggplant dishes are also great for lunch!