So the change in the mirrorless world will be even better ....

As previous speakers have already written, the adapter makes what he is almost perfect.
Processing is how I'm actually used to it from Canon, perfectly. High-quality plastic with metal bayonet. I have the "transfer" with a Canon EF 100 macro, a Canon EF 50mm 1: 8 and a Tamron 18-270mm tested. All functions have been transferred without complaint. Focusing will take considerably longer than with the kit lens. Unfortunately, I have no EF lens with STM available. I thought that the focus would work as fast with a STM lens, as with the EOS M lenses.
In general I would recommend the continuous focusing in the camera menu off, since the lenses usually always are in movement.
The control of the foreign lens also worked without problems.
Currently, the EOS M system has unfortunately only two native lenses, therefore the adapter is a good and sensible purchase.