When using this product, a little bit goes a very long way. I tap a pea sized dollop down through my t-zone, the lines around my mouth, and the spots on my cheeks right beside my nose where there are enlarged pores. I tap the product in with my fingers. My complexion is instantly smooth in spots where there was previously serious texture. Foundation sits well on top and does not separate. Sometimes I use a moisturizing primer around the perimeter of my face and where I didn't use POREfessional.
HOWEVER, I had to knock a star down for the price, there is another primer I've found from Ariatum (Korean brand) that is exactly like Benefit's Porefessional and costs $12.47 (from Amazon) for 0.9 oz which is more than Benefit's 0.75 oz. I prefer Ariatum Pore Master Sebum Control Primer and I would recommend anyone who likes Benefit's Porefessional to give it a try.