Left handedness is relatively uncommon. About 10% of the population is left handed, which by the way includes me. Some are ambidextrous or able to use both hands. I am for sure not one. My right hand sits there useless and bored most of the time.
Some positive things about being left handed besides being different: We are better at sports, especially tennis, boxing and baseball. Think for one moment of how many great left handed pitchers there are for example. Sure this might be due to right handers being used to right handed rather than left handed opponents. And we might be smarter-much greater than an expected 10% of Nobel prize winners are left handed. Great scientists such as Albert Einstein, Charles Darwin and Isaac Newton were lefties. Over 18% over US presidents including most recently Barack Obama, Bill Clinton and GW Bush are left handed (which admittedly may or may not be a good thing, depending on how you feel about politicians).
Yet all is not perfect in the left handed world. There is unfortunately a greater risk of breast cancer for left handed women. Mental health issues, especially schizophrenia are much more common in lefties. In fact about 40% of schizophrenics are left handed. Sleep disorders are also more frequent, especially disruptive sleep, in which a person moves his or her limbs frequently at night (and in my case drives the spouse nuts). Finally, left handedness is seen more often in twins.
So over all the scorecard is mixed.