I live in the fourth ward now. I moved to Janesville in 2006, not knowing much about it. I am fortunate to live on a block with homeowners. The blocks around me have many home owners too. I wouldn't move near the park. I am from a big city so I have seen much worse, not that I ever lived in worse. I purchased my first home, it's a duplex and I have renters. My renters are good, my neighbors are good. It's the area with lower end rents and mortgages so you have a lot of lower income families. I think the biggest problem I see are drunks. I have no problems feeling safe. I don't hear guns shots and don't see drug dealers, but that doesn't mean that they aren't 3 blocks down. I asked a police officer about my area before I moved in. He said the only police call he could track within the last year to my block was a parking problem.
Also you can't judge an area because of the race of people living there. I thought the minorities were going to cause the most problems in my area, but I was wrong. It's the drunk white people.
I don't plan on being here longer than 3 more years. Fortunately for me, this was just a starter home. Besides I am not from the area and miss the big city where the real danger is
Any questions, ask the cops. They get the calls.