I never used eyeshadow primer so I didn't know what I was missing, but this stuff is great. I used it for both powder and creme shadows and noticed it kept it in place all day. It seems to keep creme shadow better though, but still works pretty good on powder. It is a nude beige shade, but since your shadows going over it, it doesn't matter, the packaging isn't the best, but it's worth it. 

Loreal Decrease is definately a great drugstore answer to the higher end eyeshadow bases out there. The beige color was a bit too dark for me but since you are putting e/s over top it doesn't really matter that much. It's really easy to apply using the little applicator and your finger to blend it a bit. It lasts all day long (my skin is normal to dry though so it may be a bit "slippier" for oilier skinned people) and I've never had a problem with my shadow creasing or fading after using it. My only complaint was that it is hard to get the last bit out of the tube but using tweezers to pull out the plastic thing inside the bottle quickly fixes that.