Great brush - no leakage problem for us
These brushes have worked well for our family for 2 years.  We've had to replace 2 brushes out of 4 because our dog is unnaturally attracted to them (and steals them from the bathroom if she can), but haven't had any trouble with the o-rings or corrosion.  I always make sure to flick the brush head a couple of times when I'm done rinsing to remove excess water, which has seemed to keep the problem at bay.  If they are dropped, sometimes the little leaf springs that hold the battery can get bent, but it's an easy fix to just pull them back out.
Rating: 5 stars