Hi Robert,
Ah've come across this lens, often, in the middle of searching for other lenses. Been tempted tae buy it as well, seen it as low as £9 in the UK. As you say, less than stellar reviews but your lens and the 24/28mm have a good reputation, unlike most of Makinon's range. Although , they did build for Vivitar and they had very high performance requirements. Seems that poor QC at the factory and a high return rate were one of many reasons why they didn't survive the 80s (though that's true for many small but well regarded companies who could not compete with the technological advances of the major manufacturers). You have a good one as evidenced by a very good shot, well-taken.