We went to Suan I San just recently and were attracted by its nice enough ambience and interesting list of specials ... but we had a horrible experience.
Maybe we made a bad choice (there were other customers who looked happy enough) but our whole fish (fillet) with tamarind was a hideous concoction of small pieces of tasteless crumbed fish smothered with crinkle cut carrots, capsicum and beans and floating in a puddle of overwhelmingly sweet chilli sauce. The accompanying vegies with peanut sauce were limp and uninteresting. We tried both dishese but after one mouthful we were sure we didn't want to keep eating.
We expressed our disappointment to the waitress and rather than take any further risks, decided to just leave and try our luck elsewhere.

The worse thing, however, was the way the owner spoke to us on the way out. She quite obviously didn't give a damn how disappointed we were and thought nothing of charging us full price for the whole 'meal' - even including a BYO fee! Needless to say, we left with a very bad taste in our mouths and we will NEVER be going to Suan I San again!