Before I came across this mascara, I was convinced that there wasn't much of a difference, if at all, among all mascaras, whether they are high-end or drugstore... Until I found this one, which has quickly become a HG.
I was first drawn to the mascara because of the wand - imo, the shape and thickness of the wand are the most important factors when choosing a mascara. I like that it is a synthetic wand (as opposed to a fiber wand) that was fairly thick, which would allow for a ton of volume. The thick wand allows you to lengthen and add tons of volume to your lashes with just one coat. The formula is super black and also on the "wet" side, but I've never had any issues with it smudging or flaking. The formula is a little thick, which allows for super volumized lashes (as opposed to a thinner formula that would give you spidery lashes). I think it does a great job separating, lengthening, and volumizing my lashes.
I test mascaras based on how well they can hold the curl in my eyelashes throughout the day. Having straight Asian lashes, it's been extremely difficult finding a mascara that keeps my eyelashes curled all day. Even after a long day of work, my lashes still look like I just applied my mascara.
This is a pricey mascara - it retails for $28 in the US - but I totally think it's worth every penny. You can tell just from the packaging that it's more extravagant your typical tube of mascara. But more importantly, when you use the mascara, you can tell the difference in quality of this mascara. I've already repurchased, and may or may not have three spares just in case this product ever gets discontinued...
For people who don't want to splurge on a mascara, a really great drugstore dupe for this mascara is the Jordana Best Lash Extreme, which is only a few dollars at the drugstore! This Lancome mascara and the Jordana Best Lash Extreme are both my HG mascaras.