I am in love with Urban Decay's liquid liners.. the formula, the awesome bottle, the BRUSH!, EVERYTHING!! The color range is just awesome. I only (haha) have eight but I still want more. When I run out of perversion, I am sure that I will buy it again.
As you can see, the brush itself is very small and very precise. If you are used to felt tip liners, this could take some getting used to. However, for getting those really super fine lines - you will be LOVING the tiny brush. It might take a bit more work to create a bold thick cat eye but that is ok.. because you can be as precise as you want. I hate it when I have to work and work at a line when it is too thick to start with. With the tiny brush it is easy to ADD more instead of taking away too much.
On to the formula. It is nice, not too thick and not too thin. You can see in some of the pics where it does settle in the bottle some if you have it tipped. Also, the labels say shelf life is 3 months but I have had most of these for much longer. I only use them on myself and they have not developed any foul smell. They also seem to be never ending and have not dried out at all.
They do wash off very easily with water so not water proof but that is ok with me because my eyes do not water much. Also, you can easily apply these to your lids or lower lash line and smoke them out for a nice eye shadow base.