Lived her for over 20+ years. It's just like any other city, only with a much much bigger drug problem.

The only real issues with Manchester are the stabbings or shootings around the clubs off of Depot St but those almost always only involve people that were at the club/bar that had some altercation. Usually two drunk guys fighting over the same girl or something lame like that which escalates to one of them shooting or stabbing the other outside the club.

The homeless generally leave you alone unless they're druggies that are all drugged up and looking for quick cash to support their fix. At night you might have a knife pulled on you if you're walking through a park alone. Just stay out of parks during off hours and avoid long walks alone down the trail systems that go beneath the bridges or by the river. Aside from that it's typical city shit. Occasional car break ins, people egging cars...etc. You'll be fine as long as you treat Manchester just like any other city with problems.