Initially I hated them, as the first one I had tasted some thing like a sweet onion cream. But I've found that the taste really depends on the fruit. Every durian I've had has tasted a little different, i've had ones which tasted amazing, something like vanilla creme brulle only without the burnt sugar taste, and I've had ones tasted more onion-y (bleh). Although I've never come across a Durian whice actually smells good, they will smell like old onions and natural gas with some kind of sickly sweet overtone.
Durians are a very odd fruit, definitely an acquired taste.