I got 3 free months from stamps.com . It said any etsy seller that had never registered with them before got it. Mine didn't go through as free so I called them on the phone and they took care of it.
I love the convenience, and I have alot of customers in Canada and Australia.
The service is great, I have not paid the fee yet.
Unlike usps.com, the international first class postage is printed with the customs information on the label, I just drop the packages in the mailbox, no going inside the post office.
The biggest negative for me is I have to buy postage, I buy $100 at a time but you can buy any amount. Now I get a credit card bill every month for it, where with paypal it took it right out of the money I got paid. I have to remember to budget for that bill.