To me, it is so much for fun when it's left a surprise. I have friends who have shared the baby's sex and name months before the baby's arrival. To me, it seems not as "special" (for lack of a better word) when the baby arrives; you already know the important info. Again, this is just my opinion.
Normally, I am the "I don't like surprises" type, but when it comes to babies, I like being on pins and needles.
And then there is "getting too many opinions" woes.