I really liked Building Stripe’s API and it’s sequel, Move fast, don’t break your API:
In Stripe's case, I normally find an initial integration is a better experience than most payment services. The API is reasonably designed and well documented.
However, I also find Stripe integrations are effectively impossible to maintain or update over time. Older API versions aren't documented anywhere I can find, only the current one. There are decent changelogs with warnings of incompatibilities, but you can't write an automated integration test suite. I've never found any documentation that explains how their versioning actually works, what is affected, and how to revert if you update and there's a problem.
In practice, that means older versions of the API aren't fully supported indefinitely, nor is there a safe, systematic path to manage an upgrade to a newer API version. For that reason, we normally treat Stripe integrations as write-only code, where once you've got something written, tested and into production, it's never touched again (short of a serious security issue or the like, obviously).