As long as you're using a good brand that doesn't use more chemicals than argan oil, then it's fine to use on your face. Actually, it's highly recommended!
Argan oil is a lot more powerful than vitamin E when it comes to anti-oxidents, so as you can imagine there are tons of anti-wrinkle creams using argan oil. It's also used for clearing up blemishes and really evening out your skin tone. Argan oil is really known for its hydrating, smoothing and moisturizing properties so it's excellent for dry skin. If your skin is oily then you can still use it but not too often, although argan oil isn't oily at all so it shouldn't be a problem.
So yes, it's ok to use on your skin. I use pro naturals moroccan argan oil on my hair AND skin, not a single breakout or rash.