I recommend people have wireless Internet connected exterior cameras. Those do not pose much of a privacy risk if hacked, and they provide a lot of security compared to the low risk of compromise.
Your internal camera systems however should only be in common areas, and it should be a wired system without an Internet connection to it. Putting that system on the Internet is asking for trouble.
You want both systems for different reasons. Also, all home owners AND business owners should seriously consider at least one camera that records the street space outside. Imagine instead of the regular "Neighborhood Watch" sign it said, "All homes/businesses have exterior cameras." Criminals would go elsewhere.