OPPOSITES ATTRACT: DOES IT REALLY WORK?

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The most popular belief when it comes to romantic parings- based on the Ying and Yang principle- that two people can be the complete opposite of each other yet compliment each other and be one. This has been depicted a lot in media; best example is the sitcom Dharma & Greg about a couple who got married on their first date.

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Dharma is a yoga instructor, the daughter of hippies and a liberal free spirit while Greg is a U.S attorney, the only son of a rich (and rather uptight) couple and more cautious in attitude  but at times Dharma's funny antics rub off him enough to be her sidekick but most times he was the 'straight man' of the duo. They had  different beliefs and a lot of differences in opinion and point of view but yet remain very much in love and happy with each other.
 What happened to the notion a couple has to have a lot in common for the the relationship to work out and last forever, does being totally different actually better than being the same in the real world?
Can two extroverts be a couple? They would always try to  outdo the other with talking. Can two introverts be a couple? What sort of relationship would that be, two socially awkward people living in the same house; that can't work. What about a hot tempered husband and an equally hot tempered wife- either both would be strong enough to stand up to each other during an argument or end up killing each other- it would be like having two elephants under the same roof. 
So, maybe two opposites make the better couple. A strong manly guy with a temper could be with a quiet lady who could keep him in order with soft words that calm him down and offer her advice he would take in good part rather than from someone more bossy. An extrovert wife could be a good influence on an introvert husband as her jolliness and zest for life is just what he would need enabling him to shed off some of the shyness and be more like her; or the introvert husband could be a good influence and source of calm and comfort for the extrovert wife by simply providing her with his gentle strength.  
I've seen my share of couples who are opposites and to my surprise they have wonderful long lasting relationships. I believe most people would prefer to chose a mate that aren't exactly like them because too much of the same wouldn't bring out the best out of them. A couple of opposites may not be able to change the other but instead always compliment each other- love and understanding  being the glue that keeps them together for life.