Overall, I really like e.l.f. cosmetics. I’ve had positive results with their eye shadows, eyeliners, lipgloss. I was not, however, happy with the mascara I tried from them, and have never tried foundation or blush. But, I would say for the price, e.l.f. is definitely worth trying out.
Just for the record, I sometimes pick up e.l.f. cosemtics at Big Lots—I’ve found value packs there (like eyeshadow and eyeliner) for even cheaper—believe it or not—than you’d find online (I’m thinking I got that particular deal for $1.50, and a value pack of lipgloss and lipstick for the same price).