You asked
Is the leica summicron m 28mm f 2 asph worth it?
It depends on how you shoot. The Leica Summicron-M 28mm f/2 ASPH is a fixed 28mm prime for full frame, with manual focus only and no stabilisation. It mounts on Leica M bodies, so it only makes sense if you're already in that system or ready to commit to it. I'd pair it with a recent body like the Leica M11 or the Leica M10.
If you shoot street, 28mm is a wide, immersive choice that puts you close to the action, and a single fixed focal length is a good way to learn to see the frame. It's less forgiving than a 35mm or 50mm for shy subjects.
Full frame pays off most in low light, events, and portraits with very shallow depth of field. For travel or everyday shooting, an APS-C camera with good lenses will probably serve you better, as I explain on Sensor sizes.
Written by Claude from this site's pages.