Advantages of joint account are: easier tracking of expenses, more controlled debt levels. Disadvantage is both become responsible for others spending habits. Both should establish their own individual credit rating.
If the intent is to build credit, both individuals should be joint holders - or each individual should have their own credit card that the couple pays off each month.
I personally think it is better for you to not have a joint account with someone else because what if they decide one day that they want to go on a shopping spree and spend all of your money.