I worked 911 there some time ago. Crime was minimal in my experience. It’s a very hippie-town that is dominated by the University of Montana, which has improved recently, I’ve heard. If you lived in East Missoula or wanted to hang out with bikers and louts at the Testicle Festival or find some methies, then yeah, you might experience crime.
The weather there seemed mild to me. When it’s below freezing, it’s usually not humid, and there is no wind. I loved winters there; they were easier than any other place that I’ve lived in the American West, save Arizona now. Additionally, it’s at the intersection of five mountain ranges, and of course A River Runs Through It was filmed there, so it’s pretty all around.
If you’re into kayaking, you can play in the river at a man-made rapid.
Homelessness can be annoying downtown, I’ve heard, but I only saw that on the 911 side. The mild weather and liberal policies seem to allow homelessness a little bit more than places with harsher conditions.