WP was launched 3 years ago, WP8 a year ago. I think it was enough time to polish such a simple app like music player. But yet Spotify doesn't have most basic features I used to have in my old Winamp in the 90's or foobar2000 (if anyone remembers that one).
- no sync with desktop app, no my own tracks can be synced
- no support for local music stored on my Nokia (so spotify cannot be my the only one player)
- no filtering playlist already downloaded on the phone (must dig through mine I have no idea how many playlists)
- no searching playlists
- extremely long list of bugs (massive issue with mistakenly being offline)
- some people may like design, but I think it's very cumbersome and hard to use effectively (black/green version would be awesome)
- no last fm support
- no radio
etc, etc, etc.....
Like for a paid service it's very poor support.