It’s one of the best pieces of software I’ve worked with. I guess simplicity is in the eye of the beholder :)

It took me a while to learn the "right way" of doing Apollo. An alternative like Relay is much more opinionated so perhaps that would've helped me get there faster. But I eventually came around and now I agree that Apollo is an incredible piece of technology. I later worked on a REST API and found myself wanting to recreate much of Apollo. Especially the front-end caching layer.