PayPal is widely used in U.S., Canada and Europe but other countries haven't gotten quite used to it yet. I live in Asia and it is so difficult to find Asian stores online that accept PayPal.
I wish it would be adopted by more international stores. My job pays me through paypal and I'd rather buy stuff directly with that, rather than transferring it to my account and using a credit card. Maybe it will change in the next couple of years.