Positive: your content does not go away after 24 hours and your followers are supposed to get a mobile notification when you update a story Negative: this entire feature is on the mobile app only. Extremely anti-web...

"Series is very much a Medium product, a spare and empty place for you to fill with text and images, but there’s a dash or two each of Instagram, Snapchat (more like five or six dashes of Snapchat), Periscope, Twitter, even news apps." aka cocktail.