Spotify seriously need to do some work with their Windows Phone 8 app. The basic functionality is there and is decent enough, but I'm missing a lot of functions which is making me consider cancelling my subscription, as my Nokia Lumia 920 is my main device for listening to music. Here's what I miss:

1. There's no sensible sorting of downloaded playlists, and I have literaly hundreds of them, sortet in maps an so on. I can't remember which ones are downloaded, so I spend too much time browsing the playlistst for downloaded content. And this is kinda relatet to my next issue...
2. ...which is the lacking option of wiping all downloaded content. I actualle end up uninstalling and reinstalling the app regualarly, as it is the easiest way to get rid off all my downloaded stuff from time to time.
3. There's no radio, which makes me end up using Nokia Music (which is both free and excellent) a lot more than Spotify.
4. There should be an option to store downloaded music data on an SD card on Windows Phone, like on Android devices. Filling of internal phone memory os not a big issue on my 32 GB device, but is a huge issue for users of Windows Phone devices that have only 8 GB (and even 4 GB, yikes!) of storage. The lacking option of SD-card storage actually makes it about impossible for some users to download any music at all to their phones.

Good luck.