Bought this for my three year old as toothbrushing was becoming a bit or an ordeal. She is a fan of Cars, so thought this might encourage her to sit and get her teeth brushed. Overall it has been a success, the toothbrush buzzes after each minute to let you know to move from the top teeth to the bottom or vice versa. This means that her teeth are brushed for the recommended two minutes and she knows when we are nearly finished. The battery lasts a few days and while it doesn't have any indicators to let you know when the power is almost out, you can generally tell when it sounds a bit slower. It does need to charge up for hours from flat to get it back to full power and the charger hums a bit, but then you would expect that.
The only issue we have had was with the toothbrush heads, firstly not always that easy to find at a reasonable price. My local Tesco stocks them for around £[] for a twin pack, but not my local Asda and online they can be hard to find and with delivery quite expensive when you need to change them every three months. Secondly I noticed that after a month (using replacement head) the toothbrush head had black mould forming inside, as this stuff is harmful to your health it was binned immediately. I am now keeping an eye on the brush heads and giving it a good rinse after each use, a good shake and then I remove the head from the handle and make sure it is as clean and dry as I can get it. Despite this annoyance overall I think it has been easier to clean my daughters teeth and they are probably cleaner than we were managing with a manual toothbrush, she can even have a go herself.