Hey there :) 

I am going to soon be working on some pretty big project and one of the core features that will be implemented is the payment system. Now we ( me and a few other people ) that are working on this did a bit of a research on it and of course noticed Stripe. 

Stripe is awesome, worked with their API , pretty simple and efficient. The problem with stripe is that some features of it work only for US and we are building this web app in world wide manner. So we went the, again an obvious choice, for PayPal and with PayPal there are no "border" restrictions, tough they have some pretty scary power over you like freezing your account if they feel lie it,but that is not important right now. What I want to ask is did any of the a little bit more experienced devs had experience with PayPal API ? Any good book or a tutorial on that ( that is not their documentation ) ? 

Much thanks!