Good for reaching back teeth!
Brilliant!  I love the idea and I feel like these are a most excellent addition to brushing with a normal brush, especially for kids.  The brush heads are perfectly angled for brushing the gumline on the inside and outside faces of the teeth, areas that are sometimes hard to remember to brush due to being invisible and sometimes hard to reach.  However, the brush is not really useful fro brushing front teeth, which is why I think it works best in conjunction with a regular brush.
Rating: 4 stars