Maybe they changed something since I used it the last time when it came out but I find the UI to be horrible.
It's a Manga UI used for watching anime. I rather have a UI with beautiful animations. Saikou has one of the most beautiful UI I've ever seen in an app.
While I love Tachiyomi (J2K) as a Manga reader and I think it's the best one on any platform, it's not great as a Streaming app designed as a streaming app (I know Saikou isn't just a streaming app and you can also read Mangas in it, but I rather use Tachiyomi for that)
Edit: just checked it out. Nope still a Manga app UI for an anime streaming app with horrible discoverability and you can't switch between different sources easily. The sources are cool I guess, but I don't need those. You also can't add something on Anilist and automatically have it added to your "continue watching" list.
Switching sources def isn't a single button thing, but it's only a few clicks using the Migrate option in the 3 dot menu, it will transfer the progress you had in the previous source and the Anilist/MAL tracking.
Since I use AniChart's website directly I never missed that part being in the app, but it would be cool too.