I've tried a bunch of eye shadow primers, but this one really knocked my socks off.
I only had to use the tiniest bit on each lid so the sample size I got has lasted, virtually, forever. This stuff kept my drag-queen makeup on at the club for hours - through dancing and sweating and bad decisions. Not once did I need a touch up. I'm pretty sure had I passed out in my makeup, I would have had flawless eye shadow in the morning.
I have started using this daily before I put on my toned-down work mug, and after 8 hours in the office, my shadow is still perfect (and - full disclosure - I get super oily, so to not crease is a miraculous accomplishment).
In summary, I'll be using this forever.