Earlier quoted context omitted.
Spotify's awful discovery, and shuffle features for playlists are what keeps me firmly with Pandora. Now that Pandora lets you make your own playlists, or listen to individual songs, and download for offline playback (on airplanes for example), I don't see any compelling reason to switch to Spotify these days.
Anecdotal, but Spotify's Discover Weekly feature has ridiculously good recommendations for me and I usually end up adding half of each week's playlist to my library. The recommended music is fantastic, obscure stuff I would never have known about otherwise. My experience with Spotify recommendations couldn't be more different to yours.
For me, Spotify ended up just playing the same artist, same album even, over and over. Same problem with their Shuffle feature - I could have a playlist with 500 songs from various artists, albums, genres and more... but I'd get the same artist, same album back to back to back far too often. So often, it didn't feel random at all. Just anecdotal though.