We have owned a similar product for sometime and have never had any problems. We chose this one due the internal size, price and defrost features which are very good. Definitely recommend this product.
I bought two of these for my 9 and 10 year old, due to them not brushing thoroughly enough. The best feature of the tooth brush is the "warning" to change brushing to a different part of your mouth after 30 seconds for upto 2 minutes. This has made a big difference, as they both now have to brush for the recommended 2 minutes. Both my children's teeth are much cleaner and there's no more bleeding gums. Definitely recommend this product.
I have owned this make of brush before and due to it's incredible brushing action, this makes the Philips the best on the market. This is due to the being able to clean your teeth very thoroughly and also not causing any damage to your gums. It's a bit expensive but well worth the price, especially if you have a receding gum line and you have been told by your dentist not to brush to hard.