I was a little off-put by the headlights at first. The little jaggy bit in the middle is jarring and doesn't jive with Tesla's design language so far. It fits more with Porsche than anything. The headlights are also really far back onto the hood (a la Leaf) which isn't the greatest.
But I'm nitpicking there and when you take the rest of the car into account, it's a well-rounded design that is acceptable.
I love the S headlights and love the X headlights even more. Huge fan of the halo effect for daytime running lights. There haven't been any good shots of the 3's DRLs so it's hard to tell, but it looks like two thin lines going in crazy directions? Kinda like those Mercedes:
I'm worried that they're too thin on the 3. They look kinda fragile. Not from a structural point of view, but they make the headlights look flimsy and I want my car to have a commanding presence. I'm OK with the design of the two lines, just would like to see them beefed up a bit. Also, neither the X nor S has two separate halos, so there's another inconsistency.
Again, I don't know if those lines are supposed to be DRLs or what. I sure hope the only DRL isn't that big white spot on the top. DRLs are a huge part of modern car styling these days since they're always on, but a lot of people don't seem to talk about them.
All in all, headlight design is passable. Doesn't blow my socks off like the S/X, but then again, I wouldn't expect it to since it's a cheaper car.