Famous for its casual wear industry, the downtown indeed looks like an open-space factory. The Arabic language seems very present in the area, sign of the vitality of the economical partnerships or maybe also a trace of the ancient Silk Road which had Quanzhou as a major terminus.
Buses are pretty erratic and there's almost no taxis, they don't use counter anyway so just use one of the thousand motorcycle drivers at each corner. Don't hesitate to negotiate the price (¥6-8 for a downtown trip).
The three main public parks don't have anything special and the overall atmosphere is grim, possibly due to the suburban factories and the crazy and very honky traffic. But the small streets downtown have such an authentic flavor, mixing the different markets to genuinely old temples. Do get lost in the urban maze, and the direction staring people are taking will indicate you the way to go.
Outside of the city are several towers on the way to the Golden Beach which is never very crowded except during national holidays.