I can say for a fact that Latisse works. I had thin, short, light auburn lashes before. Now, at not quite 4 months I have very long, slightly thicker, dark brown lashes. They are really amazingly long.
I have brown eyes and I have not seen any darkening of my eyes or the area around my eyes.
I have been using the product on my eyebrows and it seems to be making them thicker too.
I strongly encourage everyone not to use the Latisse brushes though. They are too wide and pick up too much product. If you use their brushes you will end up with Latisse all over you eyeballs, all over your cheeks etc. The one time I used their brushes I ended up with bright red, itchy, swollen eyes the next day. It was terrible. I'm 100% certain it was due to the fact that the Latisse brush just picks up too much product and smears it everywhere with no precision. Now I use a tiny eyeliner brush from Sephora. I clean and sterilize it in Sephora brand cleaner/sterilizer every night and store it in a ziplock bag. That has totally eliminated my itching, redness etc.