Benefits Roller Lash mascara is designed to curl and lift lashes, rather than just providing length. Think of it as a hybrid of a eyelash curler and mascara, you're simply cutting out the middle man. It's modeled on the idea of a hair roller (hence all the super cute marketing with rollers!) and it 'hooks 'n' rolls', which results in super soft, curly lashes.
The brush is shaped slightly differently to a normal mascara brush, and it's also smaller so it can get to those pesky edge lashes. When I used it I really felt the curve of the brush rolling my eyelashes into a curl. And although I'm lucky enough not to have particularly straight lashes, I definitely noticed a difference. My eyes looked brighter and more open.
Volume wise, I would say it provides a good amount of volume. It's a great option for a daytime mascara. The lightweight formula means it isn't too OTT for an everyday product, but it can be layered on for a more dramatic evening look. It also does a solid job of separating the lashes, avoiding the clumpy, spiders legs look (which is never ideal). It stands the test of time without flaking and doesn't smudge.
(Top - Before application. Below - After one application of Roller Lash)
So, Benefit have done it again. I'm completely hooked (no pun intended) and I'll definitely be snapping this up when it's released in March.