Not the greatest, but definitely not the worst. It doesn't clump, it darkens lashes and the result is nice. However, it does not add volume, does not make my lashes look noticeably longer and is not the best Maybelline mascara I have used.
All in all, I am happy with it in the sense that it was a freebie - I would probably be slightly disappointed had I had to pay for it. The brush is nice and small so it is easier to coat all lashes and it is fine to use as an everyday mascara for more natural looking makeup.
I liked this because it didn't clump. It doesn't add much volume but it does what it says- it defines your lashes making them look more natural, rather than bold and elongated. However over time I found that the formula became thick and lumpy, and thus began to clump a bit.