It's well-suited for a creative writer who is comfortable writing essays or short fiction. It's especially well-suited for writers who are focused on writing essays based on personal experiences. I'm not sure it has the tools at this point for someone who wants to serialize a novel or long-form non-fiction book. I'd like to see better multi-media tools for writers/content creators who are fluent in written and audio-visual methods of communicating.
It's really difficult when multiple people are editing the blog at same time. Some things change or get overwritten due to which have to reload the page multiple times. Would like to see an experience just like in Google docs.
Substack is the DTC version of traditional blogging sites - you own everything, both upside, and risk, which appeals to me more. Compared to Blogger, the ability to monetize and site interface is night and day better. Compared to Medium, which I think has a better interface and content curation abilities, Substack's advertising and promotion of your work are much better because they don't rely on premium members like Medium - it can get very click-baity there.