First, it's very conveniently located, on the corner of Hang Buom and Hang Giay, in the heart of the Old Quarter.
Chances are you'll find yourself passing by anyway as you go for a stroll, so you might as well stop in for a peek.
Second, it's a beautiful, well-maintained temple that serves as a good example of what small temples in Vietnam are all about. And finally, it's still very actively used for worship — note the extended hours on the 1st and 15th of each lunar month to accommodate those who regularly come with offerings to burn incense and pray. A guide can't be hired on site so if you're keen on the whole low-down, ask at a hotel or travel agency.