Surang's is in my standard lunch rotation. I've never been here for dinner, so I can only comment on my many lunch experiences.
For whatever reason, there are a lot of Thai places close to my office, but Surang's is my favorite. The lunch special is a great deal, which comes with the soup of the day, fried egg roll, and fried won ton. The lunch portions are generous. Service is always very friendly. However, because there's only one server, if you're there during a lunch rush and the restaurant is full, the service may not be as quick as usual. Normally that isn't an issue though.