I have the Urban Decay Primer Potion in Original. The potion itself comes with a wand and the formula is of a light nude shade. When I apply it, I just put 2 small dots on my lid and blend with my pinky finger. The formula is thin which makes it easy to blend. With this primer on my lid, eyeshadow application is easy and smooth, the colors are even, and it never creases. The last part is really important for me because I've always had issues with creasing on my lid.
The only issue I had with this primer is that I had to be extra careful in applying it only on my eyelid and not have it touch my under eye area. I remember noticing these light clumpy spots on my inner eye and under eye area as if the concealer had solidified. I thought it was my concealer at that time (I believe I was using the Tarte creaseless concealer), until I noticed one day while blending the primer potion that I accidentally dab a little bit of the primer on to my undereye area and these are the spots that get clumpy. I’m not sure if it was because of the thick consistency of the concealer that I was using, but it was really hassle to remove that I had to redo my whole look.
Other than that, I was very happy with this purchase. Mind you, I haven’t tried a lot of eyeshadow primers in the market. However it is very affordable, of good quality, and lasted me more than a year so it’s worth the purchase for me!