We never used one, though my husband suggested buying one when my son was born, as it was winter and he saw that his friend used one on her baby. At that time, I thought it was unnecessary, but I now feel bad for my little one, though if he`s in a good mood, he`ll just giggle at the shock of the cold wipe.
I wouldn`t care about the electricity use - it`d be soooo minimal, but these HK apartments are not designed for lots of electric things (despite being this kind of society), so it`s just annoying to have to find a plug for one more item.
I would never do the whole `hot water thermos cotton pad` thing. just thinking about the effort makes me shudder. I just want to get that diaper change over with as soon as possible, as does my son.