Review (5/5): Use a little common sense, folks!
I'm sorry but I just don't see how all these people are getting so much water into the battery compartment. Are you submerging the whole thing just to rinse the bristles? Are you spitting up all over it? Are you holding it vertically while you brush/rinse? Are your kids dropping it in the toilet? I've had mine two months and don't have a bit of trouble holding it so the bottom end never gets wet...or the brush end of the head either, for that matter. Just rinse off only the brush itself holding the brush end DOWN. Use a little common sense and take care of your things, for heaven's sake people. It doesn't take a genius.
edit - I've now been using mine once or twice a day for over two years and have had NO problems with water leakage, corrosion, burnouts or breakdowns. Rechargeable AA batteries last up to 6 months and I change the brush/head once a year although I'm not sure it needs it even then, the new bristles feel just the same as the old ones, despite Sonicare's recommended 3-4 month lifespan. At $12-15 a pop I'm sure Sonicare would like you to replace them far more often than really necessary. No special o-rings have been needed. I still can't understand how so many people are reporting water leaks & corrosion unless they just need special supervision to operate any mechanical device.