I think it’s more a gimmick than an actual useful feature. A Siri shortcut for a web page? Just add the page to your favorites or add it on the home screen.
For apps, for what I tried I didn’t save time that much either.
Opening a webpage is one thing it can do. I would never use it what way (that’s not how I use workflow). But saying it’s a gimmick is just ignorant. Developers need to assign intents for the in app actions for it to be truly useful. Shortcuts can leverage the current useractivity that handover and continuity uses today. But intents are much more useful and apps have to update to use it.
The auto generated shortcuts for the mainstream will get a lot better after iOS 12 is released. The ones you create depends on your imagination.
I’ve created some workflows that change the data in a url scheme for an app. And in one tap I’ve created a form filled in with the correct information etc.
What I like the most about workflow now becoming a part of the OS is they now work in the background and you can launch them with Siri. Powerful stuff