Buying a multifamily home with people already in it

[Jonathan Kramer]

Is this a good idea to purchase a double house with someone already renting out one side? I'm ready to buy my first property, and I really like this place; however, being new to this i don't know if it's a good idea to buy it with someone already living there. What do you think? Also, they're paying 100 dollars less then the average rent for that neighborhood and type.