I was never really big on primers until I started wearing eyeshadow frequently. And because of the climate in this country, it's impossible to wear eyeshadow the entire day without primer. It's just too hot that it'll melt and crease within a couple of hours.
The first eyeshadow primer I tried was MAC's Prep + Prime Eyes. It's super smooth when applied and even feels lighter on the lids compared to other cream eyeshadows I've tried. It's extremely easy to blend your eyeshadow after application.
Does it work? Well, it does help your eyeshadow last longer... but not by much. During the day, my eyeshadow would start to crease after 4 hours or less. When I'm inside an air conditioned building at night (which is quite often), I have better luck in making my eyeshadow last for about 8 hours.
I tested this is both humid and cold weather conditions to see if it would perform differently. Unfortunately, it did not. Maybe my lids are super oily? I don't know. I hope MAC comes up with an eye primer that lasts longer.