It's cheap and chaotic. It's the best place to find second hand clothes, DVDs, CDs, books and various souvenirs. The best thing about it though is the food section.
If not for buying second hand stuff for affordable price, then go there to buy from the food section. Show up early though, as early birds catch the worm. The good things go out quickly. Bring cash!
In the food section, try out the purified shark. If you ask nicely, the seller might even give you a taste.