I think the main cons are:
1) Loss of privacy-residents will know everything about you
2) Lack of 'distance' from work~in other words you're always at work, even when not.
3) Related to the first two~residents often have no boundaries and will not have a problem knocking on your door whenever they feel they need to, regardless of the actual situation.
I have never lived onsite, but the people on my staff who did would often report these cons.
For the pros~I believe
-Response time in an emergency
-Ability to see and hear what's really going on with your residents
-Your presence may also deter any negative activity