One of the advantages of a mirrorless camera, like the EOS-M, is the very shallow backfocus requirement. The distance from the lens mount to the sensor is quite small, allowing use of just about any series of lenses on the market. All that is needed is the correct adapter, a need that several specialty manufacturers have addressed with products. The result is that the camera is useful in a wide range of photographic experiments and projects.
I have had fun simply shooting with these old primes and the EOS-M camera. Sometimes I will grab a single lens and just go someplace to play with the camera for half an hour, sort of a self imposed creative exercise. Using one of these manual focus lenses brings back memories of my first years of film photography, before the days of auto-focus.
Combine these old lenses with an extension tube, and the rig becomes a macro-photography setup capable of fairly high magnification.