What can't the Olympus OM-D Em5 do as well as a DSLR/SLT camera?

Thanks for your reply.

I have heard from a few owners that have said the EVF is actually pretty good with little or no perceivable lag, but I think the AF issues (which sound the same as those with the NEX cameras, resulting from only having contrast detection rather than phase detection AF) are the dealbreaker for me.

It's a shame, because I think this camera probably has better IQ/features than whatever I will end up with/can afford in the DSLR market.  Also, although I have serious concerns about the ergonomics with the grip, it would be nice to have a more concealable camera with me in Manhattan on an upcoming pleasure trip so as not to scream, "I'm a tourist!"

Anyway, this has helped to further define what I need and want in a camera, so thanks again.