Joint accounts here since before we were married - married 16 years ago. we both maintain our own sole accounts as well into which an equal amount of personal spends goes into and we both have a savings account. Wages go into the joint account and everything is paid for from the joint account. personal accounts & said money is for personal treats, birthday/christmas and occasionally anything we could not justify from the joint account such as a new iPod when the old one is still working...
My brother & his wife have the exact opposite - married for the same time. what they earn is their own money, they pay half the living costs each, she pays her petrol money for my brother driving her somewhere (e.g. to the supermarket to buy her food), she pays for her food in the supermarket, separate trolleys (and same if they eat out!) she earns 4 times what he does and their marriage is failing.