Whether romance compatibility tests are legit or not, I really don't know. In my opinion and experience I have found both sides of the argument to be true.

On one hand, I have seen a great deal of correlation between, say, astrological signs and people's personality and, furthermore, what a combination of two signs would yield. My girlfriend and I are a sagitarius and a libra (respectively), and according to most romance compatibility tests we are a star couple. I feel that way, and even though we have our fair share of arguments and stressful times, in the end the good times do match up to what the tests say.

On the other hand, though, there are many more components to personality than just when you were born. How you were raised and what experiences you had also determine the type of person you are and what other types of people you like. So, to that extent, romance compatibility tests hardly ever take those things into consideration and you have to do your own examination to get to the bottom line.