Ignoring the obvious goady one on here (and their putrid, bile-filled comments,) I agree that Diana WAS virtually a child, and 19-20 IS a young age to get married. (Just because more people got married younger in the late 1970s/early 1980s, that doesn't change the fact that it's still young!!!)
But at the same time, I believe she knew what she was doing.
I quite like Camilla and Charles too, but I also very much liked Diana. I don't think there were ANY winners in that scenario - the triangle they were in. Charles wanted to marry Camilla but The Queen wasn't having any of it. She wanted him to marry someone pure and young and never divorced, and a virgin (although no-one can know for sure if Diana WAS a virgin.)
But yeah, Charles being coerced into marrying Diana, didn't result in happiness for him, Diana, OR Camilla, and I am glad he managed to forge a life with Camilla eventually, and find happiness with her. I am also glad Diana found happiness eventually too, with Dodi. Very sad that she was taken from us so young, but I believe she was happy when she died.