It works just as well as the MAC Black Track gel eyeliner. It lasts all day, and doesn't really smudge.
The only downside is that it is a little less "black", so sometimes I have to go over it twice.
The brush that comes with it works well. I have a separate gel liner brush, but occasionally I use the stock brush too, and the results are just as good.
Mine is relatively new, so it hasn't dried up yet (like my MAC Black Track), so I can't comment on that. THis is currently my go-to gel liner.