Good evening from Cambodia,
I'm actually travelling in Thailand and Cambodia for 2 weeks and stopped by Narin as I heard it was one of the only reliable tailors in Bangkok.
He is indeed a bit stiff but one might argue that it's out of discretion and a tad of pride. Anyway, he's quite firm about time needed to make clothes. 4 weeks and 3 fittings for a suit, 2 weeks for a shirt, not less and a minimum order of 3 for shirts (reminded me of Turnbull & Asser).
Anyway, I've got quite a number of MTM and bespoke suits mainly from Europe (Paris, Rome, London) and consider to know a well-made suit when I see one as well as a reliable tailor. Having tried various tailors years ago in Thailand (e.g. Danny's, so-called tailor fo the Danish Crown) and in Indonesia (e.g. Anika Tailor), results ranged from dreadful to barely acceptable, less so at the time as I had much less experience. Now this being said, you usually get what you pay. If you think you can have an amazing suit within 24 hours at 100-250 USD, you're truly mistaken but I think most people on this thread know that already.
As for Narin, we ruled out the suit as I wasn't in town long enough but we launched an order of three shirts. Fabrics were reasonably priced under 3000 THB for Japanese 1-ply cotton. There are some Loro Piana, Zegna, Thomas Mason but significantly more expensive and at a price not appealing to me as I would order bespoke shirts in Paris at 220 EUR in Alumo fabrics. I also opted for the "handmade" option at 1500 THB that Narin offers for handmade stitching, buttonholes and an unfused collar. I gave a shirt from Luxire that fits well as an example. It was quite funny seing him analyzing the shirt as "fused collar, plastic buttons and so on". I guess that after challenging him on various things, he expected me to bring him a bespoke Charvet shirt. Well, sorry my friend but I don't travel with that sort of clothes. They stay at home :)
Anyway, I saw one of his suits made for a client and it looked quite good. The lapel was way too narrow for my tastes, vents too low and there was a stitching on the lapel I didn't like but these are personal tastes. The buttonholes, which are usually a good way to judge a tailor, were quite nicely made and on par with WW Chan in HK. Not bad, especially considering the 22,000 THB for a CMT fully canvassed price. However, I have a HK based tailor who's travelling and gets me the same kind of work at -20% less so I wouldn't have tried in the end, or only out of curiosity.
All this to say that Narin is indeed reliable and knows his stuff.