I am a regular at this teahouse, and I wouldn't go anywhere else for good tea.
They serve your tea in a yixing teapot and walk you through the gongfu cha ceremony.
The tea is top notch. They have a wide selection of oolongs and pu'erhs. Definitely try the Golden Leaf, and the premium Pouchong. Excellent Tiegwanyin King too, if you're willing to pay the price.
They have very good greens as well - I recommend Yun wu, yun ya, and mao feng.
The owners are very friendly and helpful in choosing a tea for every occasion.
The shop itself is also worth a visit just to see the beautiful woodwork and all the teapots.
Great place to sit down after a long walk around old port, unwind after a work day, or wrap up a meal on a night out.