Streamlined navigation and personalized search are pretty self-explanatory, designed to make the Spotify interface more intuitive and helpful. Spotify says the redesigned search page is "the new one-stop destination for artists, albums, podcasts and more," whether you know what you're looking for or want to explore something new.
Endless Artist Radio is not dissimilar to the exploration feature that made Pandora so popular. Choose a favorite band or song, select the Artist Radio playlist and you'll get an endless stream of music based on what you've chosen. The playlists are updated regularly, and are also downloadable to play while you're offline, so you can take your K-pop obsession (or whatever you're into) wherever you go.