It is something a lot of good coaches disagree on. So essentially, not a make or break thing unless you are pushing big poundages. Wendler looks up when he squats. Rippetoe down. Some other powerlifters look down/ahead, some look up.
I look up when I squat. I have found the tendency for many many people looking down is also do cave their chest in, which makes you lose tightness. Looking up helps you (or me and many people I have trained with) think about keeping your chest up, back tight, and elbows down. You can do this looking out and down too.
Also, when I say "looking up" I am not talking about the ceiling!! I am looking out AND up, or slightly above parallel (i pick a spot on the wall at or slightly above head height when unracked, then keep my head looking up at it in the hole).
I think often times "looking up" gets translated in a newbie's head as "look at the ceiling" or "crane your head up". This is not right and can lead to the neck pain the OP was talking about. What many newbs end up doing is hunching over their upper back like they are at a computer chair, and then trying to look at the ceiling. Recipe for disaster there. Chest is down, back is loose AND the neck is craned up.