I bought the Mazooka last time around for a 7yr old. Works great, one marshmallow at a time.
Couple annoyances are batteries died very quickly and the marshmallows had started to get stuck inside the tube. Not fun to clean. To fix that issue we rolled the marshmallows in some extra powdered sugar to make sure it was not sticky at all and also sprayed a little pam on a paper towel and wiped the inside of the tube with it. That cleared the problem right up.
We set up helium balloons around the backyard to use as targets and it shoots wonderfully with good aim. After a while the adults took over and I think we ended up having more fun with it than the kids.