Eminem's movie was based on 8 Mile rd! That's at least a half an hour away. And some of the scenes were from the Alter Rd area (which is also a half mile away).
There is a bubble around the downtown area that gangs and thieves just don't bother to cross. Too many police and cameras. I would avoid anywhere east of I75, south of the Lodge. Dearborn is a nice area. It's home of Ford. So it's really built up nicely.