I've heard that Madly is a blush that needs to be applied to the face rather than swatched to be fully appreciated. I can kind of see why the sentiment exists, but for me, I honestly don't discern a humongous difference between how it swatches on my wrist and how it appears when worn. It's probably slightly more red/orange/pink rather than purely brown/tan, but nothing distinct. The colour transformation might be more pronounced depending on your skin tone though.
To me, Madly is better defined as a warm bronzer with subtle terracotta tones and fine microshimmer. It does have more colour (in the sense of earthy ochre hues) than a more traditional bronzer which might be less warm and more yellow, brown or golden, but I can't imagine using this focused on the apples of my cheeks like a conventional blush. It's more of a hybrid blush/bronzer that is swept along the cheekbones and blended onto the cheeks for an overall bronzed, softly sculpted, "healthier" look. As KathleenLights so evocatively put it, "It reminds me of a goddess walking on the beach with flowers in her hair and a big seashell necklace, talking about life's mysteries, wearing this blush." Immediate Birth of Venus vibes.
l-r: Chanel Soleil Tan de Chanel, Charlotte Tilbury Sculpt, NARS Luster, NARS Madly, NARS Laguna
Compared with a bunch of other bronzers and NARS Luster, another illuminating hybrid blush/bronzer, Madly is somewhere in between the golden brown NARS Laguna and more orangey NARS Luster, with a hint of the shimmering, cooler brown Sculpt shade in Charlotte Tilbury Filmstar Bronze & Glow.
I'm somewhat on the fence with Madly. I don't love it, but I'm still glad it's in my collection. It's a useful, versatile, "throw it on in a rush" product that acts as a blush and bronzer in one. Colour-wise, it's a bit too brown and similar to a regular bronzer for the effect on my skin to be anything particularly special or unique. I almost wish there was more of that promised "seashell pink" to provide a point of difference. Still, the quality is top notch as you'd expect from NARS, it goes with anything and provides natural definition and a sun-kissed, enlivening warmth to the complexion.