This short summary by Jordan Merrick is very promising.
Since its acquisition by Apple, I've been very skeptical of the Workflow app. Apple tends to behave like a child excited to buy a new toy only to leave it in the driveway to get run over at the end of the day. While Workflow has received a few minor updates since the acquisition it felt like development was stalled. Clearly I was wrong, so take the following opinions with a grain of salt.
The Limits of Siri
I think Apple's new Shortcuts app is a recognition that Siri, as a secure and private assistant, has major limitations that alternatives from Amazon and Google do not. Shortcuts will be Apple's advantage in the assistant market, but only if they can make it approachable.
Siri suffers from a lack of contextual awareness for me as an individual. It often fails to provide useful information when I need it. Amazon fails too, but the Echo is generally more helpful than Siri is on my iPhone. As I recently said, this gap is still small but Amazon is getting better at assisting me much faster than Apple is. Shortcuts changes the focus for Siri from an assistant that figures out what I might want to an assistant that does what I say, no matter how complex.
My hope is that programming Shortcuts becomes simple enough (and voice controlled) so that anyone with an iPhone can build complex routines simply by suggesting patterns to Siri. I don't expect this soon but I hope it's on some whiteboard in Cupertino.
I also hope the long term strategy is to build beyond trigger phrases and provide contextual queuing. I'd like Siri to understand that I have a Shortcut to play my favorite podcasts, I leave for work at the same time every morning, and I usually listen to podcasts on my commute. Then I'd like Siri to combine that information, all on my device, and begin when I pull out of the driveway.
By combining the complex actions I manually craft with small pieces of contextual data, Siri can leap past other assistants. But Apple needs a way to enable users that don't want to learn about variables or logic controls. I don't know how they make that happen but unless the Shortcuts team figures that out, Siri will never be more than a novelty for most customers.
I suspect iOS 12 is the test bed for Shortcuts and iOS 13 will see the consumer friendly version.
As a side note, check out Jordan's iPad Collective. He publishes reviews and tips for iOS users without being too noisy or being a commercial for Amazon links.