Yep, not all that accurate, but they sure are fun.
The kids use ours all the time. When outside, they get a dead tree branch with lots of smaller branches, stick pop cans on the ends of the branches and blast away. (Safety glasses of course)
Inside we generally use the cardboard box with newspaper at the back of it. The newspaper is because we also shoot pellets into it. In case we miss, we have a large piece of heavy geotextile hanging behind.