I can't live without it!! At the first sign of a cold, I take it every 3 hours for 3-5 days. I may or may not get a cold. If I do, then I switch over to Cold-eeze (lozenges, NOT the subligual pills. Yuck!). I do Cold-eeze for another 3 or 4 days.
The combo may not help me avoid a cold altogether, but it does decrease the intensity and duration. Normally, I'll feel bad for only one day and even that day is do-able and I can function normally aside from a snotty nose and sneezing. If I take some cold medicine on top of it, I feel quite normal although a bit swollen in the head from sinuses, but nothing major. I'm back to normal within 1 week (as opposed to 2.5 weeks with no airborne and cold-eeze) and exercising within a week of being sick.
If I'm around someone who's sick or I'm travelling, I dose with Airborne about 2 or 3 times a day for a week. I don't get sick.
Now this is great for a cold. But I have found it does absolutely nothing for the flu.
Editing to add: If you've already got a cold, it probably won't help. You have to take it the very moment you feel that tickle in the back of your throat. Before then, if possible. If you're already sick, I'd recommend going straight to Cold-eeze.