The obvious benefit of having a maid or maids is that they make your own life much easier. If you don't have to cook and clean and if you have someone to help look after your children, life becomes much less busy. You can be more relaxed and less stressed. You can have more time for hobbies or recreation.
The major con of having maids that I have seen personally is the effect that it has on children. It is easy for the children to become spoiled when there are maids around. The children don't have to do things for themselves. They also are being cared for by the maids but they know the maids are just employees who are, in a sense, inferior to them. This makes it easy for the kids to come to have a lack of discipline.
Having domestic help allows one to concentrate on other issues because domestic tasks have been delegated to the maid.
Hiring domestic help stimulates the economy. It gives value for the services rendered.
One loses a sense of privacy, if one hires help. From the laundry, to telephone conversations, these mundane things are now privy to an employee.
Having a maid can be socially awkward. The idea of hiring someone to clean your clothes, sheets, bathrooms, etc., may create an uncomfortable feeling. Particularly if one did not grow up with "help" around the house.
Having a maid can make one feel that their home has been professionally cleaned as opposed to the hit-or-miss approach of doing the work alone.