Tested on film only.
A very compact design, that performs in a charming way.
My sample, at least, had a very particular way of rendering the highlights, whit a smooth pleasing graduation of luminance values.
It is quite sharp, too. Even the borders, but well stopped down, to f/5,6 or f/8, are quite sharp.
In short, a nice little ultra-wide, that will fit into your pocket.
Rating: on film