Is Paypal IPN always necessary?

Question

If I set paymenttype to instantonly, is there any reason to set up IPN? Don't I get all the information I need from do_express_checkout?

Answer 1

There will be a bit more information returned in the IPN. The IPN will also update you as well if for some reason PayPal places a hold on the payment, or a charge is filed against the transaction.

Answer 2

What Chad said is right, but practically speaking there's no reason, and the vast majority of EC integrations make no use of IPN.