My non-profit group decided to go all the way with inflatable bounce house rentals during our last community-wide block party. We not only rented several inflatable bounce houses, but also inflatable water slides and a castle. The rental company provided an employee who could set up the equipment according to city codes, and he also taught our volunteers how to supervise each of the inflatable houses. Children may want to stay in those things all day, but once they start getting tired, they can get hurt very easily.
I thought it went very well in general. We probably should have done a better job with advertising the water slides, since some children did not know to bring swimsuits. The bounce houses were very popular, and we only had two minor injuries all day.