I have been using Latisse since April 6, 2009. My natural lashes are long but somewhat sparse and very blonde. Best news is that now they are really long, so they look awesome with mascara on.
I have reduced my use to about once a week right now, as I found that using Latisse more often than that made my eyes itchy and my eyelids redish. I will keep using this even though I did not get darker lashes, but they are long and getting a bit thicker. I may try going on it again on a daily basis to see how it goes.