Review (5/5): I have 4 of them -- still working since 2010
These are great toothbrushes but many people seem to be having reliability issues. Not me, though. I bought 4 of these in 2010 for my family. All of them are still working and I have replacement heads delivered regularly via Amazon's "Subscribe & Save" program. Great! We use them with rechargeable batteries; they last almost a month between charges.
But let me repeat what others have said: you simply have to LAY THEM DOWN TO DRY. Don't stand them up on the base. I had read that advice in the reviews when I bought them. My kids and I quickly got used to laying them down after use. However, my wife really had trouble learning this and she kept leaving it upright. Her toothbrush would occasionally stop working so I would open it up and let it dry thoroughly and it would start working again (although there is some corrosion inside.) She finally learned to lay it down, though.
Highly recommended (unless you are unwilling to slightly modify your behavior for a bargain!)