This ruan zhi oolong from Fine Thai Teas is a good example of one of the two main Thai teas, along with jin xuan oolong. Both are names of cultivars, or tea plant hybrid types developed in Taiwan from crossing existing plant types (number 17 and 12 in a numbered series, respectively). This cultivar is almost always prepared as a lightly oxidized oolong in Thailand, as it was in this case, although of course it could be made into other types of tea. This flavor profile and feel are just what this tea is supposed to be, both of which remind me of teas from Taiwan.
rolled ball oolong, the typical style
The predominant flavor component is an earthiness, a mineral element that is hard to completely define. A second flavor element is a mild spice, similar to nutmeg or cardamom (and no, it doesn't taste like Chai, not even a subdued version). There is also a hint of a floral component.
I realize I've just said the tea tastes like a nondescript mineral, spice, and flower, so basically I'm saying I don't know what it tastes like. It would be easy to adjust that to saying it tastes like flint, nutmeg, and orchid (which is really a group of flowers anyway), and I'd sound more competent, but really I'd need to train on smelling more rocks and flowers to be more certain. Nutmeg is really a relatively complex flavor, with the flavor profile, warmth and sharpness exhibited across a range, so it sort of tastes like part of what nutmeg tastes like (to me), the warm, rich component, not the sharper aspect.
One other notable characteristic is the aftertaste / finish; the taste lingers long after drinking, in a good way. This can be even more pronounced in some teas from Taiwan but is significant for this tea.
nice looking leaves
When I first started drinking oolongs I really loved this tea type. I don't mean to say that my palate has matured past it, or that it's inferior to the teas I tend to prefer most now, but preferences can just change over time. I still love this type of tea, and it's the kind of tea that's great to have as one of many types to drink when you feel like it, not really a type of tea I would get tired of.
It's also nice that lighter oolongs are easy to brew, so it doesn't matter if one uses boiling point water (more on brewing temperature and timing in this post), or lower, or messes up timing by a good bit. Another nice aspect of decent versions of such teas is that they brew a lot of very consistent infusions. With black teas or darker (more roasted) oolongs it's easy to Western-style brew two good infusions and then depending on all the factors maybe a third, but this tea is fine for twice that.
It would even be good as an iced tea, although tea enthusiasts tend to not typically go there, unless something unusual happens, like the Bangkok hot season. Even then I'd just drink hot tea and sweat even more, but I've been experimenting on making iced teas for my wife and her mother since they'd been drinking some bottled teas--not as nice a taste, almost certainly not as healthy. I recently read an article claiming you shouldn't drink iced tea or cold drinks in general in hot weather, that it's bad for you, but who really knows about that, people seem to be getting away with it.
Compared to a jin xuan, the other main type, this tea type tends to be less sweet, and a bit earthier. Jin xuan can have a notable creaminess to it, even natural flavors that resemble butter to some extent. Decent versions of both are pleasant and easy to drink, with good flavors, and better than average versions can be very nice, but in general the two teas are consistent.