Review (4/5): READ THIS TO END CONFUSION
Look - Life ain't perfect - neither are we. We increasingly live in a time where YOU GET WHAT YOU PAY FOR.
First Premise: Anyone who still manually brushes is asking for trouble - the environment ain't what it used to be and groundwater poisoning is a big part of the story of deregulation. I've spent thousands and hundreds of hours in dentists' chairs - currently much of the lower left quandrant of my smile is cerac - and I brushed faithfully daily for decades - up and down brushing with daily flossing (no matter how intense)does not cut it. Thus, the incredible evolution in electronic toothbrushes over the past decade.
Second Premise: AC Outlet Rechargable is better and the motor will last twice as long (assuming proper care). However, Battery Run is FAR MORE CONVENIENT. I have found that with proper maintenance - these units last approximately two years. Proper care means unscrewing the brush head and cleaning and drying the connection at least monthly if not weekly. After a month of brush use (or thereabouts you'll find alot of gunk - mostly from you and your tube of toothpaste - inside there - I use q-tips and paper towels to clean it) Proper care means checking the batteries for corrosion as well as charge when the unit slows down. If you find signs of corrosion in the - clean it out thoroughly. For checking batteries - use a simple aa/AAA/C battery tester - an invaluable tool to these days.
Conclusion: You spend about $10 bucks a year on the unit and $10 to use two brush heads per year as well. After two years, if it's broke or the motor has slowed down significantly - even when new batteries are installed - chuck it. If you've got the money, $20 a year for a new unit annually is not really a whole lot compared to what dental work costs these days. Actually, mine unit is going on three years old and is working fine - although battery life does seem shorter.