This is a question we hear often. The most important thing is that you keep up with regular brushing.
While not all power brushes are the same, many studies have shown that in general they are more efficient in controlling plaque than manual brushes. The movements of the electric brush make brushing easier and more effective. In addition, some brushes, like Sonicare, produce sonic vibrations that are difficult to mimic with a normal toothbrush. Other electric brushes like Oral-B and Rotadent have small heads that help you access hard-to-reach areas of your mouth.