Singapore made lenses are prone to mechanical defects
bokeh on photos taken from close distance on cloudy day with no light points may be ugly.
Optically, it is the same lens as Carl Zeiss Planar 50mm f1.8 and Rollei Planar 50mm f1.8 in QBM mount. That means very nice rendering, sharpness, centre sharpness even wide open. Bokeh is a very subjective affair. I personally like planar bokeh, but a lot of reviewers are not pleased with it. To get good results, one needs to know the lens and use it according to its strengths. That means that in some situations Ultron (planar) will create ugly background, but it is easy to avoid it.