Pak Tai Phattalung (ปักษ์ใต้พัทลุง) is an awesome southern restaurant with a huge menu on the canal road. Everything is in pots out in the open, so feel free to peruse their curries, grilled fish and chicken preparations. Be prepared though - some of them are extremely spicy. Make sure you get a plate of raw vegetables to dampen the heat.
One curry plus rice and vegetables runs about 40 thb, a good meal for two is about 120 thb.