Mary Lou really is the perfect highlight shade - it's a beautiful champagne tone that's not too pink and not completely yellow either (great for makeup artists as it's pretty much a universal highlighter!) It's finely milled so goes on so smoothly and blends out beautifully unlike chunkier highlighters (I'm thinking the MUA ones and the Urban Decay naked highlighter) which can just look a bit too much.
Do I even need to mention the packaging? It's the prettiest thing ever and makes me want to buy everything else from The Balm just so I can look at it! My favourite brush to apply it with is either a larger fluffy brush for a more diffused natural look or the Real Techniques setting brush, which allows more control and precision. The price is a little steep, but still considerably lower than the MAC msf's - plus it looks as if it will last forever. So, overall, I wouldn't definitely recommend this to anyone who prefers a powder highlighter and likes to go a little bit bolder with their glow! I couldn't live without it now.