Is the Thai coffee 100% Arabica?
Yes.
Coffee cultivated in the north of the country tends to be Arabica, whereas the coffee that is cultivated in the south is more usually Robusta.
Until very recently (the past two years) I had never come across Thai coffee, and last year, had to consult my notes to recall that I had really liked it, whereas, this year, when it appeared, I remembered how much I had enjoyed it.
In any case, from what I have read, over the past few decades, Thailand seems to have developed an impressively serious coffee culture, especially in the capital, Bangkok, and in the northern Chiang Mai region (which is where the coffee I am currently drinking comes from), along with a few other regions from the north.
Tasting notes serve to remind us of a surprisingly strong Kenyan influence (such as can be found in some local varietals that have been crossed with some Kenyan varieties, such as SL28, and in what tasting notes on some specific coffees refer to as "washed in the Kenyan style").
Light roast styles predominate.
However, I would describe the coffee as sweet and smooth, and it is a coffee I now realise that I have come to like.
Moreover, I would also note, and this is a subjective observation, as personally, when I am at home in the temperate climes of those isles that lie off the coast of the sometimes chilly north west of the continent of Europe, I tend to be exceedingly partial to the addition of milk and cream in my coffee - whereas in hot climes I will more readily reach for espresso, and will happily take my coffee black - Thai coffee lends itself well to the addition of milk.
I suspect that this may be a strong local cultural preference, as what is referred to as - or known as - traditional Thai coffee tends to be served with condensed milk, thus, Thai society and culture are very comfortable with the concept of milk - and its derivatives - added to coffee; however, unlike some coffees, in my experience, this means that the coffee from Thailand tends to lend itself very well to the addition of milk.