You’ve also got a few options to demo it! If you want the siri shortcuts one, go to the page and you’ll see that a bunch of sections are available for preview. If they seem like a good fit, then you can buy it.
Also, while not nearly as useful as the siri one, you can always try the (free) Workflows course since it’ll be like a more limited version.
My review: every one I’ve purchased has been well worth the money (photos, OF, Shortcuts). Some (e.g. Drafts) are free, but would have been worth the money if I did have to pay. I even wrapped a gift using the MacSparky field guide! (although the rest I just put in bags like a neanderthal because I’m lazy). The cost is low enough that even if it isn’t that great, it isn’t a huge loss like lots of online courses (~$200).