No one will ever be, thank God. The question is whether the differences are things that will drive you apart, or magnetize you together. It's also essential to recognize that the longer you've been single, the more set in your ways you become. So don't let small things come in the way of your long-term happiness. Accept that your partner will enjoy different activities, do things differently and have different opinions.
Issues pop up even with the most compatible couples.
Friends of mine spent their first year of marriage in vicious battle over whether toilet paper should roll from the top or the bottom. They eventually resolved this crisis, and are now quibbling over replacement of the toothpaste cap. Still, remove as many land mines as you can beforehand. Love can conquer a lot, but it can't hold together a couple who are going in separate directions. If your not sure whether an issue is surmountable, consult a rabbi or trusted counselor.