This liquid liner are like the other pen like liner (ex.kat von d, physicians formula, dollywink) The only difference is the way the product is dispensed. Some people may not like the other pen like liquid liners because it can dry out fast if its not used. I personally have not have had this problem but friends of mine have.

Packaging ...
 The MJ liner has a twist knob on the top of the pen for you to twist out the liquid. Just think of those twist up lip gloss but in liner form. The cap has a spring like feel to it when closing. This is a plus because it ensures that minimal amount of air can get meaning the liner won't dry as fast. When the product is brand new, you have to puncture into the product to get the liquid out. Everything is sealed to ensure that when you open it for the first time, you know its brand new. I really like the way its packaged because to me, its like they tried to take all those little flaws other liners have and revamp it making it better.

Liner itself ...
The color I got was BL603, its a navy blue color with a hint of sheen to it. The first swatch and the first couple times that I used it was really pretty. The more I used it though, the more I contaminated the brush with black so now its a shade of gray. The consistency of the liner is a bit watery. Be very careful not to twist the knob too many times or else you will be stuck with a blob of liner.
It lasts all day without smudging.. it comes off easily with makeup remover .. the color does fade a little bit throughout the day though.

Cons ...
As much as I love the idea of dispensing out what you need, It gets a little tricky and annoying sometimes. It makes applying with this liner not consistent. Sometimes you will have too little product and sometimes too much. The opaqueness of the liner also depends on the amount of liner is dispensed. If dispensed too little, the liner seems almost sheer meaning you have to dispense and build up the color to the desired opaqueness.

Overall, I do like this liner and I can work with the flaws. For someone that doesn't use liquid liner everyday, its nice knowing that i'm not obligated to using it because i'm scared that its going to dry out.