The formula is supposed to give a "glow finish" while setting makeup for "up to 12 hours" in two shades--Translucent and Medium Deep. It is described as having "sheer coverage" that "blur the look of fine lines and imperfections." The powders have a silky, finely-milled quality and are sheer but neither is colorless, and I noticed that the Translucent darkened my foundation about half a shade overall (I'm about light to light-medium). Both shades deposit a soft, barely-there shimmer, but it's somewhat visible close-up, so they result in a good deal of luminosity when applied all-over. I found that I preferred the look of the original Loose Setting Powder for most of my face and using the Glow version on strategic areas for a candlelit glow as the original formula gave my skin a smoother, more pore-less finish than the Glow version.
The powder did help extend the wear of my foundation, and I'd agree that it definitely kept my foundation looking fresh for between 10 and 14 hours, depending on environment, formula, and how much foundation I applied (or didn't apply). In general, I would recommend this powder only for someone who likes a very dewy finish, doesn't mind visible pearl/sheen on the skin, and is light-medium or deeper (or doesn't mind a warming powder if one is fairer).
The average rating based on all reviewed shade(s) in this formula is shown below.