We actually live close to the Garden Night Market; just a 10 minute walk. We have met people from all over Taiwan who make this one night market their "must" stop for an evening in Tainan. It's got all the snack food that is famous in Taiwan and those that are unique to Tainan. It gets crazy-crowded sometimes, even on the hottest and most humid nights. We used to go there even then, but the humidity with the crowds now keep us away. Even so, for the visitor, it's all part of the ambiance.
The one thing I wish there were more of is the "stuff," the nicknacks markets are famous for in Taiwan. This one has the food, of course, and lots of clothes, games, and cell phone covers, but not the little nicknacks of Taiwan.