> They're great for big business at scale
> They are wonderful for big business
I (sadly) completely disagree with this. There are still so many basic things they don't expose, and it feels like you're fighting an abstraction designed for a start-up that doesn't want to think about the complexities of payments at all. For example, you have to fight a battle to get the card IIN exposed to you. There's no way to see the electronicCommerceIndicator (ECI) for Wallet payments (it clearly has it, since it's shown in the dashboard if you dig deep enough, but it's kept from you). For their Direct Debit integration, they apply limits on the payment amounts you can initiate, but there's no way to actually see the current value of what these limits are. The same Direct Debit integration also doesn't let you customise the payment references used (GoCardless lets you do this to identify e.g. individual invoices on customer bank statements).
Some of the APIs clearly haven't been thought through - e.g. for disputes you can't programmatically retrieve the evidence submitted by the card issuer. Which means you can't build any sort of sensible custom integration for handling disputes. And besides, they don't even support pre-arbitration (which the card issuers know about and take advantage of frequently because they know their decisions outwith the card scheme chargeback guidelines cannot be challenged effectively).
Their Google Wallet integration is worse that Braintree's and doesn't support the web-based flow.
There's not nearly enough visibility when things go wrong, particularly with their 3DS integration (which was failing for Samsung Internet browser users for us, and we had to fight to get looked at - nothing ever got published on the status page despite the fact this significantly affected your chances of securing liability shift) and you have to escalate via an account manager to get any sort of useful support case response.