There are a lot of advantages to be had from a private security service operating in your neighbourhood. These types of services have many of the same advantages and drawbacks as the general private security services, although because they are often acting in a public area they are often more limited than, say, a private security firm working in a commercial property.
Neighbourhood security services are usually provided in the form of rapid response teams whom are trained to help their clients in emergency situations, but in more general situations, ones which aren’t quite as serious, they act as an active presence restricting the ability of criminals to act in your neighbourhood (a lot like a neighbourhood watch). They also work closely with the police to help keep your streets clean of loiterers and help punish other crimes like fly-tipping.
In conclusion, the services they provide can play an important role in enhancing the security of all those in the neighbourhood, but they also provide a number of other roles to ensure that the neighbourhood is a nice place to live as well.