I get increasingly pleased by the modest 50/2 AI. The imaging qualities are not particularly outstanding, but simply good (except maybe the sharpness wide open, which is modest). The small size and the handling make a difference with many other lenses. The recessed front lens makes a shade superfluous and is a good protection, especially since I never use filters. So that small lens is a confidence-builder, which maybe contributes more to good shots than perfect optics.,
My other favourite in that category is the Zeiss 50/2, a better lens in every respect (except flare on stopping down), but it is quite a bit heavier, and 10 times more expensive by the way.
Unexpectedly, I managed to get good night shots too, at least when stopping down a bit was possible. The 6-ray stars may also look appealing at times. First shot at f/4, second one at f/8 (thanks Df).
I made my Milano trip with Zeiss 25/2, this 50/2 AI, and the Tamron 90/2.5.Three different styles, but all very usable.