The first thing I noticed was the disclaimer on the box noting that a slight tingling sensation is normal. Turns out, "slight tingling" is quite the understatement. After a few seconds, I felt little sparks of warmth under my eyes. A few minutes in, I wondered if I was having a weird reaction. (One R29 beauty editor also uses this and says she's never felt the tingling sensation.) But I pushed on, because beauty is pain — or slight discomfort — and I wanted results.This one delivered them. Immediately after using it, I felt my undereye bags tightening just a bit and feeling significantly softer and more hydrated.The serum, unfortunately, doesn't claim to do much for dark circles, but concealer glides fantastically across the surface after I remove the pads. Hey, you can't have it all — but I got more out of this treatment than any of the ones that came before it.Eye Lift Firming Treatment, $68, available at Sephora