Guerlain's Le 2 has two brushes. The main brush is a firm, short-bristled brush that surprisingly coats the lashes well and keeps the mascara from clumping. The second brush is a teeny-tiny bottom lash brush that I also use to add definition to the corners. It's so small that it reaches those inner corners well too.
The formula is pretty good. I like the way it applies. I get some length and some volume. Nothing over the top but better than the way my lashes normally look and it lasts me the whole day even without primer or a lash booster. I don't get irritation or fallout. Overall, I'd say they really hit the mark with Le 2. I'd like to see Guerlain come out with a waterproof version though. This one resists water rather well but it's not waterproof. If they come out with that, it's sure to be on my wishlist. It's expensive, I will admit. I'm not particularly looking forward to shelling out $36 every month for it but when the drawerful runs out, this is the one I'm going to repurchase.