It's OK. I've tried: EF 50/1.4, 85/1.8, 70-210USM, Tamron 28-75, EF-S 55-250 STM, 40 STM.
The Tammy is a slow focuser to begin with, and likes the M even less.
The 50 and 85 focus fine for static subjects. They will miss moving subjects. I've enjoyed both, and find they are a good size. The EF40/2.8 also focuses fast, and has nice output on the M. I just don't know what to do with that Focal Length, so I returned it. The 55-250 STM is pretty darn fast, too (for non-action shots), but I decided I didn't need that focal lenght.
The EF 70-210 USM is an old lens, and it focus hunts quite a bit with the M, but that lens REALLY old -- I think mid-90s, so the algorithms are probably really old.
I was delightfully surprised at how well the EF USM primes focus, but I'm mainly doing landscape and still life and portrait. I use my DSLR for action.
Hope that helps.
Here are some example shots with the 50, 85 and 40 on the M
I would summarize this way. If you have Canon lenses, and you have the M for the 22 or kit, then go ahead and put them together. It's worth the adapter. If you have lenses, but not the body, I think the body is worth it, if you are shooting mainly scenic/vacation/static. Get the body with the 22, IMO. If you have neither the body nor the lenses, and/or if you want to shoot action, I'm not sure the combo is the first set-up I'd invest in.
50/1.4
20131020-20131020-IMG_6719 by
wt2100, on Flickr
85/1.8
20131015-20131015-IMG_6586 by
wt2100, on Flickr
20131015-20131015-IMG_6576 by
wt2100, on Flickr
40mm/2.8
20131008-20131008-IMG_6512 by
wt2100, on Flickr