The only real issue with Paypal is unfortunately a huge one if you're unlucky enough to get caught up in it - their overly-aggressive "holds" on funds in accounts. Other than that their customer service is better, their site easier to use, and they have the benefit of a huge network effect already in place. Paypal even called me a couple of days ago to verify that a transaction (I was the buyer) was legitimate. In the past they would have just rejected it and left it up to me to contact them to convince them otherwise.
