I picked this up a few weeks ago from Boots but it's also available online. It was £6 (link) which I thought was pretty reasonable. This is the first product from the Soap & Glory cosmetics range that I've tried.
The packaging is what you'd expect from Soap & Glory; it's a bit quirky and bright but still practical. It's basically exactly like a felt tip pen.
I should confess that I'm a total devotee to my Bobbi Brown gel liners and when I do want to wear liner, those are the ones I usually reach for. I've tried several liquid liners in the past and have always found them difficult to work with.
Soap & Glory say that this liner features 'our unique INKJET™ colour release & Gloss–Fix™ finish to give a rich and intense colour. The foolproof marker tip creates two looks - Fine point for a natural look or thick edge adds a dramatic flash!'
Their description is fairly accurate, I found I could get a fine line or a thicker one relatively easily. The nib is not very flexible though so it wasn't the most comfortable or precise application-wise.
As you can see from the swatches, it does have a glossy finish once dry. I really liked that look as I find black liner sometimes looks really flat when it dries so I was impressed with the finish. However, this transferred pretty badly on me when I did a thicker line.
Would I repurchase this? Probably not, I prefer my gel liners for their staying power but I'll continue to use Supercat when I want a finer line.