Bought this recently along with the Ansmann rechargeable batteries (thanks Busy Dad for the top tip), for anyone that's interested I bought 4 x C Cells, Ansmann MaxE rechargeables 4500 Mah, makes it expensive, but definitely works without the issues found in other reviews. The butterflies don't come out fast and furious but they do come out a few at a time. My son who is nearly 3 loves it, and I've put it as educational for him as it will help with his hand eye coordination, or at least hopefully it will once he gets past screaming with excitement when he sees the butterflies shoot out the top!
The butterflies are a little fragile so you have to be careful with the little ones handling them, and the nets are a bit basic but essentially they work.
I would highly recommend this product, it is fun, but bear in mind the additional cost needed when adding on the rechargeable batteries. Even with the additional cost I've bought it and expect it to provided hours of fun!