I've lived up here for close to six years now as both a student and now a career academic and there are definitely visible signs of gangsterism in the city if you know where to look for it - a ton of the bars and small cash-only businesses (an interesting feature of Liverpool is the sheer number of pubs/shops/restaurants that still do not accept plastic) close to where I lived as an undergraduate round the Smithdown/Allerton/Wavertree areas were gangster run and shootings were a not infrequent occurrence (in terms of the UK, which has very little gun crime in a global context.)

In addition to the more organised drug distribution rings there are also numerous street gangs operating throughout the poorer parts of the city, ultimately it's a story familiar the world over; the poor parts of Liverpool (Norris Green, Anfield, Croxteth, Dingle etc) are essentially as deprived as the UK gets and anywhere there's entrenched poverty and despair with little hope of relief is going to breed crime, organised or otherwise.

This is the latest shooting on Smithdown, about 5-10 minutes walk from where I used to live and where I pass en-route to work pretty much everyday: http://www.bbc.co.uk/news/uk-england-merseyside-31239282

Within a couple of days of this a man also got hit and killed by a bus and a driver had a heart-attack and drove into a lamp post all within about 500 yards of each other.

Aside from this aspect I would just emphasise what a great place the city is - the negative reputation that still persists is a couple of decades out of date; it has some of the greatest architecture in the country with the highest number of listed buildings outside London as well as the largest collection of internationally acclaimed theatres and galleries aside from the capital, not to mention some of the best and most easily accessible nightlife anywhere in the country, oh and 7 UNESCO world heritage sites!