You asked
Is the leica apo summicron sl 28mm f 2 asph good for street photography?
The 28mm f/2 is a sensible street focal length. On full frame it frames as a true 28mm, wide enough to show a scene with its surroundings, and f/2 gives you room in low light. On an APS-C Leica it frames like 42mm, which is a tighter, more portrait-leaning view, so think about which body you'll use.
The street guide puts a quiet, easy-to-carry camera ahead of spec sheets, so the body matters as much as the lens. Options from this lens's list include the Leica CL, the Sigma fp, and the Panasonic Lumix S9. Check the lens page for the full list of bodies it fits.
Written by Claude from this site's pages.