Detroit is not as bad as it used to be; not as good as you want it to be. I wouldn't walk in residential or underpass areas at night, but around the business downtown area, especially the stadiums and theaters, it's usually a pretty lively area during days, and especially during events.
If you ever need to go somewhere and there's sketchy parks or whatever in between, we do have Uber/Lyft like any other major city, and that's a very safe way to travel.