1. Packaging is critical to marketing a product. If your product is relatively unknown (in other words, a product that isn't quite tried and true yet), then packaging could be the key to success. Shoddy packaging will indicate shoddy products in a consumer's mind, and the product will probably not make it off the shelves. Your product's packaging may not end up as iconic as Coca-Cola's, but you should aim to create packaging that customers will scan the shelves for while shopping.
When I think of how a product's packaging may have influenced me, I immediately think of Market Pantry products. I'm always tempted to grab those products off of the shelves because something about the packaging is appealing (perhaps the red and white color scheme adds to the appeal). However, I never buy Market Pantry products, because I remind myself that even though the box and the price tags look appealing, the product inside is definitely second rate.
(I did a Google images search for this picture, and it brought me to a website announcing that this particular product had been pulled due to unlabeled peanut allergens. Good thing the packaging didn't fool me.)
2. Perfumes tend to have iconic packaging. In order for me to buy a perfume, it has to look as good as it smells. In fact, the packaging has to pass the test before I even consider the scent. The past couple perfumes I have purchased have been Armani Code and Burberry Brit (which is probably the more recognizable of the two).
Another product that I consider to have iconic packaging is Starbucks. You can recognize the logo and the green lettering anywhere.
Marlboro cigarettes also have very iconic packaging. I'm definitely a non-smoker, but I'd recognize the Marlboro packages anywhere. (Notice how Marlboro takes advantage of the red and white color scheme that Gordon mentions.)
3. As far as usability goes, gum packages stand out as regular usability failures. Although iconic, the packaging of Orbit gum is just annoying. The package always opens in my purse, and I'll end up many times with individual pieces of gum in random places in my purse. Orbit packages are an example of an improper balance between attractiveness and functionality.
While Orbit gum may be too easily opened, most electronic and technological devices are difficult and sometimes impossible to open without scissors or something of the sort. I recently bought a USB flash drive, intending to use it right away, but according to the impossible-to-open packaging, that just wasn't going to happen.