It is not as comprehensive as other vehicles and there are a few formal tests you can look up. It really only claims to reduce the severity of frontal impact under good conditions for vehicles and pedestrians. Outright prevention is limited to situations you could handle yourself. Pedestrian detection is effectively non-existent in my experience. Vehicle side of things has a fair bit of false positives, though it's never taken action (unless I was in ACC.) Direct sun, rain, hills, turns, lane changes, people changing lanes in front of you - all fool the camera system really easily.
More modern systems actively prevent collision in multiple directions, even taking autonomous evasive maneuvers is relatively common and affordable these days. At the high end vehicles can do this in complete darkness, in bad weather, and detect things like large animals. We aren't talking about any of this on the latest generation of MINI, but maybe next?