We like the control of a pen, dislike the faff of gel liners with separate brushes. Our favourite liquid liners are definitely the dip style felt tip liquid liners. You get great control with these.
This Collection product was at a pretty good price but was very average. It stung our eyelids a little for the first couple of weeks, but the main issue was that the colour was not really as dense as we would usually like.
Not terrible/average in all. Our favourite so far is Rimmel Exaggerate (or the Clio Kill Black Eyeliner Pen, not available in the UK) which gives a really opaque line.
PROS: A good-quality tip for producing nice shapes/lines, relatively cheap
CONS: Colour bit watery
2 out of 5