I actually live right downtown, less than a quarter mile from Comerica Park and Ford Field. My wife and I just moved here in July. Before that we lived in the suburbs. The big impetus was that I got a job here. So now I walk or take the people move daily and my wife commutes to Dearborn, which is about 8 miles. She would ride her bike but it gets shady on the outskirts of Detroit.
Most of what has been said is true. Downtown is very safe and the city has taken steps to ensure that it remains so. The worst thing would be for crime to be up downtown, because right now one of the few bright spots is events (sports and entertainment). The city is also targeting areas and making sure they get support, like Southeast Detroit near Mexicantown and a few other areas. In my mind, there is a lot happening down here and we are slowly approaching critical mass. Quicken just moved 2,000 employees here in October on top of the 2,000+ they already had down here. Blue Cross Blue Shield just moved about 3,000 down here in the summer. Right down the street from me there are major renovations going on to 3 buildings which will include about 1,000 apartments. From what I have heard, there is a long waiting list to get into these places. I checked out an open house at one and it was packed. Dan Gilbert, the Quicken Loans founder partnered with a few other wealthy enterpreneurs to start a venture fund. They are looking for web startups and have made about 10 investments, then bring those companies downtown to incubate them. Another company, GalaxE Solutions has about 200 employees here and they are in the process of hiring 300 more right now.
So all of that said, you can see the improvement on a monthly basis, as more jobs come, as more people move downtown things improve and there is less and less "shadyness" so to speak.
As for prices, it depends on where you live. You can certainly get a house for very sheap in some nice areas. My wife and I didn't want to commit to another purchase (we are renting our old house out now with plans to sell it in the spring...)so we rented an 800 square foot loft for $850 a month. We definitely could have found a cheaper place, but the buildings we looked at that were chepaer were much older and were just not our style. Parking and water are included in our place, but we pay gas and electric. All in all, much cheaper to live here than our other house, even just considering the rent vs. mortgage and all of the utility bills. When you factor in transportation, it is a huge savings.
Like I said, Detroit certainly isn't perfect, but there are a lot of great things happening down here. I'd certainly encourage anyone to come check it out...there is a really great vibe going on and it is great to be a part of.