I've been living in Montpellier for 6 months, and I love the place - great climate, good infrastructure (if you find accommodation near a tramline, transport around town is very easy). Lots of things to do, and heaps of events, especially over the summer months. As Bev says, there are a lot of young (and not so young) single people in town, so it's fairly easy to meet people, especially if you join a club or an association for whatever activity or sport you enjoy, even for a short period.

In my experience Montpellier has no more problems with homeless people and crime than any other moderate-sized French city. If you're sensible and can "non merci" politely you'll have no problems. There are parts of town that foreigners probably don't want to live, but these areas are very obvious when you visit them, and easily avoided. Lyon is similar in this regard.

I've had no problems with people wanting to speak English with me, although there is a strong and rather interesting English/American expat communityin Montpellier who is fun to get to know (go for a drink at the Vert Anglais any night of the week).

A lot of residents here are from other parts of France anyway, (Montpellier is a popular city among the French too) so in the city itself, the local accent is probably less of an issue for non-native speakers than in the countryside - you get used to it after a short time anyway.