I will chime in as well. I am also originally from Bay City. I have most of my extended family and lots of friends there.
I own a rental in Bangor township and I just finally sold a foreclosure flip in the city that took forever to sell. I would caution you to stay out of the city, and instead look into Bangor or Monitor township. The city tries to crack down on out-of-town investors. I can understand that they don't want slumlords, but they are rather indiscriminate about harassing all out-of-town investors. I worked hard to keep my place looking nice, but they nit-picked about my property the whole time that we were working on it, when an owner-occupied across the street was horrible (lawn not mowed, high weeds, not shoveling the sidewalk, etc). I was actually improving the area (by fixing up a house that sat vacant for quite a while), the house turned out so nice (too nice - I over-improved it - but that's a whole other story).
There are some very nice condos along the river, but the prices are shockingly high.
Another issue with Bay City was trying to find honest people to work. Even with all my connections there, it was near impossible.
I don't know if the city will experience a turn-around or not. It seems like it's possible, given the regeneration that is happening along the river.
The number of vacant/abandoned houses continues to be quite high. But the city is very short-sighted and doesn't understand that it needs outside money to come in and infuse the economy with cash, jobs, housing.
So just some thoughts around my experiences. I still want to invest in the area, but it's not as easy as it looks :) .