I've paid for Crysta using Paypal every single month since SE enabled this payment option. Payments are instant and reliable and secure. I consider SE adding the Paypal option as one of their finest QOL improvements since FFXI was launched.
It's not that I had issues with the payment system in general, it's that I had really poor experiences with paypal support. They had at one time introduced some sort of new account link function between them and ebay and when I went ot buy something they asked me about this, and I'm like sure, link the accounts. A payment for what I was purchasing went through without any confirmation or chance to choose the funding source like I usually do (When I thought I was just linking my account), and the payment went through on the wrong funding source so I had to arrange a refund with the seller and then pay the correct amount using the payment I intended to use. I tried to get help from paypal first and they didn't seem to have a clue what was going on. This was like a year ago or so. I haven't had major issues since, but that was a very frustrating experience, both for me and for the seller I was interacting with.