Thanks for replying Stef. At the risk of succumbing to what Charlie Munger described as 'Deprival Superreaction Tendency' (basically, refusing to cut your losses and move on), I am going to continue and complete the course, since I'm almost done and have spent so much time with it already. It seems like at least some of it is still relevant so far and I should be able to learn a thing or two about PayPal's API yet. I'll check out the other courses you suggest. Thanks again.