We would not be addressing this question were it not for the fact that (in our view at least) this is a matter of some doubt. We have discussed elsewhere whether opposites attract, and in general the answer is no. However, that is not the same as saying that opposites cannot get along. Extreme introverts and extreme extroverts would make a strange coupling, and would be inadvisable.
Still, when one of the couple is more introverted or extroverted than the other, that is usually a good thing. So long as the gap is not too large, it is typically an advantage when the personalities of the couple complement each other, rather than being simply a mirror-image of each other. Each personality type comes with different strengths, which together make for a better combination, so long as the couple act as a team.