Best way I can describe misskey as a user of it is that it's like mastodon but if they implemented every feature request possible. I mean it literally has a toggle to convert your text into cat speak for no other reason other than the dev felt like it. It even has its own markdown language to give your text crazy effects because who wouldn't want an emoji amplified 4 times that spins and changes color?

It uses activitypub as well so it's entirely interoperable with mastodon instances (although some functions like quote posts or the custom markdown language aren't formatted as nicely when viewed from a mastodon instance)