The bike motor makes zero noise. In fact, because this has an internal CV transmission and a belt drive, my "acoustic" bike (which has a chain and a derailleur) makes more noise.

The battery needs a special charger, unfortunately (though that plugs into a regular socket). I know people with long commutes buy or make a second charger for the office, but it's not an issue for me. I suppose I could carry the charger if I went somewhere and wanted more range, but it's heavy!