What makes this slightly different to other highlighter/concealer pens is the texture which is quite thick and very pigmented. On first use I found that it dries very quickly and becomes too dry to blend out. The trick is to use a damp brush or sponge so that you don't blend it away but you can manoeuvre the product to where you want it.
The effect is quite good though, decent coverage of dark circles and any redness. From a distance it looks flawless and I was impressed with how bright and clear my undereyes looked. However on closer inspection it does dry in to wrinkles and clings like a limpet to any dry patches on your skin.
My suggestion if you are going use this product for the brilliant highlighting and concealing properties (there is no shimmer which is good) then moisturise extra well to prevent it drying too quickly and settling in to fine lines/dry bits.
I like this product for highlighting too, bring it down the from the undereye area to a point on the middle of the cheek in a triangle and blend for really well defined and chiselled cheeks. Use above the jawline from ear to ear to add even more depth to sculpted cheek hollows.