I'm afraid I don't have the 50mm macro, but I do have the 35mm macro. Like the other 43 lenses I've used on m43 bodies, focusing is slow, so I suspect it will be the same with the 50mm. The results are nice, and I usually use a tripod, so the slow focus isn't a huge deal. This was the first 43 lens I tried out on my e-p1 and I felt like I had gone back in time to the mid-1980s as far as AF speed was concerned.
The upside is it makes AF with the 14-42 kit lens seem positively speedy in comparison!
Of course having said that, I have to admit I use my e-p1 more than any other camera I own, so obviously for me, AF speed is fast enough.