I had them done several years ago by a celebrity make-up tattoo artist teaching classes at my cosmetology school and I love it. As a make-up artist myself, you need to make sure the person really knows what colors work for you. Some of the lighter browns and darker blondes tend to shade a tad reddish, so ask if they can avoid that.
They apply the needle in little dots and feather like strokes, for a very natural hair look. Be sure your eyebrows are waxed first, and you will really need to consult with the artist to make sure they get the right shape. She should draw the shape on with a colored pencil that you can approve, then she will follow that design. Of course, other tattoo artists may not do this same method, but it really helps so you know they aren't going to do some hideous arch.
Now, having it done, not very painful at all. They use a numbing gel, though you can still feel pressure, nothing like an actual skin tattoo though, I know!
You have to wear gel (I think vaseline if I remember correctly) on your eyebrows for about a week, they will look huge, puffy, black and shiny! You will look and feel like Groucho Marx for about a week, and when the skin starts to peel, you have to avoid peeling it off!!
After it is all healed and done, you can enter the world again and feel beautiful! Now, eyebrow tattoos are not very deep in the skin because facial tissue is so fine. They fade after several years. Due to the peeling process, they usually do a light layer, and then a second light layer a short while later to really make it more permanent.
So, I had mine done about 9 years ago, never regretted it, but the tattoo itself is almost totally gone expect for a few small spots I can see only because I know where to look. I have dark eyebrows, but a bald patch, and that is where the bulk of the tattooing was done, plus along the brows and on the ends for a very nice and natural point.
Verdict, try it!! ps... try having them colored first to try it out. You will love it I think. We color eyebrows all the time in the salon.