Coke zero has its own unique flavor, with maybe a hint of Coke Classic. If you were blindfolded, and you drank some Coke Classic, and then some Coke Zero, you would be able to tell that they were both Coke products. Just barely however. The taste is a lot more defined in Coke Classic, but with Coke Zero the taste is so subtle, that you feel like you're tasting liquid more than soda. The taste is weak in short. I suppose that can be good if you have a sensitive mouth, but if you're looking for something with a bang to it, this is not the drink for you.
Coke Zero seems like it has about a third of the carbonation of Coke Classic. Coke Classic starts to hurt your mouth if you take a big sip and hold it in your mouth, while Coke Zero does not. This takes away most of the point of drinking soda for me, because you might as well be drinking "Coke Zero Juice: With 10% Carbonation!" Keep in mind that Coke Zero has less carbonation than usual, which makes it seem watery. This can also take away from the enjoyment.
Coke Zero has a very simplistic packaging design on their 12 "Fridge Pack" can set. It's pretty much a red Coca-Cola logo over a black background, always with the obligatory silver wave. Coke made a good choice when they decided to keep the packaging plain and simple. The font for "Zero" seems a little gimmicky, but when you need to sell a product, you'll do what you need to.
I was content with Coke Zero, but not impressed. The taste is a subtle version of Coke Classic, that seems unique, maybe a little watery. This can lessen the experience if you're used to Coke Classic. It CAN be enjoyed however, when you try the flavored versions Vanilla and Cherry.