Good, not great
My husband has the rechargeable sonic care, which I loved but didnt want to spend alot of money so I order this battery powered one. Its alot more aggressive (stronger vibrations) and heavier than the rechargeable one, and the bristle head is larger, however the cleaning power is the same. I haven't seen any corrosion, but I've only had it a month. I am careful to wipe it clean after brushing and use minimal water.
Rating: 4 stars