My impressions are based on only two use-cases from the four-pack of samples. My first impression -- "sample" is inadequate to describe the quantity of vinegar included; it is generous.
At once, of course, I opened each bottle and smelled it. This, really, when it became clear that there was something nuanced about this vinegar. Mind you, I'm hardly an expert -- I had assumed that all vinegar is distilled. Whatever one calls the process used to make these vinegars, it appears to produce a vinegar that's full of character.
Last night I cooked a stifado -- a Greek beef dish which plays on an aggro-dolce palate, the sweet provided by red wine and red currants, the sour by feta added at the last minute and 4 tablespoons of red wine vinegar added as the pot was deglazed before the simmering phase. So a lot happened to the vinegar in the following two and a half hours. Still -- and this may be a hallucination, since I didn't have a control version of the dish made with standard ol' red wine vinegar -- the stifado came out particularly well in my view.
And that's the problem, for me; I can tell that the vinegar is good, and I want to say that it outperforms my other vinegars. It probably does, but I haven't made an empirical study to demonstrate that!
So I return to the sniff test. I really like the red wine and cider vinegars; the Chardonnay version will require some experiment, as will the rice wine one.
All in all, I'm very pleased to have these -- not just because of their obvious refinement but also because it's good to support small companies doing something interesting.