Build quality is good but the large lens barrel with a small front elements makes the lens look unbalanced and funny looking; definitely not the most handsome lens around. One nice feature is its close-up capability, which focuses down to 0.23m with a magnification ratio of 1:5. Quite good for a wide angle lens.
The image quality is very good. Wide open, a little soft and contrast is lacking (but not as bad as the Komine made 24mm f2). I am quite surprised to find that this little lens has very good micro contrast which gives the picture its bite when stopped down. On the NEX-6, the outer edges are acceptable at f8, but not as good as the center of the image, so I presume it's even worse on full frame. Too bad this is the Canon FD version and I can't try it on my 5D II. The bokeh, to me, looks distasteful, like most wide angle lenses, but your mileage may vary and may find it nice. But not to me.
Vivitar 28mm f2 FD Mount made by Komine. Click for larger.
Bokeh - Sony NEX-6 & Vivitar 28mm f2 @ f2. Click for larger.
Bokeh #2 - Sony NEX-6 & Vivitar 28mm f2 @ f2. Click for larger.
Mask - Sony NEX-6 & Vivitar 28mm f2 @ f5.6. Click for larger.
Tree - Sony NEX-6 & Vivitar 28mm f2 @ f8.