Has the problems of any large UK city, but the notion that it’s uniquely violent is (these days) way off. The city did previously have a disproportionate issue with knives (surgeons at the Glasgow Royal Infirmary became world leaders at patching-up stab victims at one point) but this has improved a great deal over the last ten years.
As above, it’s a pretty buzzing city today, whatever you happen to be into.
MTB-wise, there’s decent riding options within 30 minutes drive and some of the best UK riding within a couple of hours.
Be sure to eat here at some point:
http://www.oxandfinch.com/
The one thing that the city doesn’t do particularly well at is outdoor drinking options, with the few decent placed generally rammed on hot days (they do happen occasionally). Whisper it: Edinburgh’s a bit better at this.