http://en.m.wikipedia.org/wiki/Rare_Earth_hypothesis
The more they look, the more unique the Earth becomes.
Yes, Earth is unique, just like all the other planets. One hundred years ago the existence of other planets was mere speculation. They had no compunctions about believing that our solar system was the only place in the universe that had planets. We look out into space and we are finding more and more planets out there. We still can't see all that far or all that well, so it stands to reason that we have barely scratched the surface as far as the actual number of planets even in this one of billions oh galaxies. The more planets we find, the less unique earth will turn out to be..