Quick suggestions for upcoming updates:
I use Spotify like I used my iTunes. When I like a song I swipe left on mobile to quickly add the song to my "Library". This way I can shuffle my entire Library with different genres of music.
This is great for streaming music in the car as well because I use the cache function of Spotify to reduce my data usage. In Europe data usage is still not unlimited which plays an important factor for most Spotify users. The cache function is not properly used when listening to predefined playlists that update regulary because it will most of the time be an entire new song that has to be streamed.
When going abroad we'll have to use roaming which is very expensive most of the time for most Spotify users. Downloading my entire Library with the push of a button is very dangerous. If someone has a smartphone with 16GB and he downloads his entire Library to listen to music abroad it will most likely crash his phone because the amount of songs is too large for his smartphone.
It would be great to have, just like iTunes, an auto playlist based on your own songs in your Library with "most recently added", "most popular". This way you only have to download that playlist for listening to music on the airplane, bus, metro, car... when going abroad.
When following a playlist, or even your own playlist, it would be great if freshly added songs to that playlist would appear on top. Now we have to search for the "blue button" to see which song is newly added.
This brings me to the following suggestions:
1. Make it possible to shuffle playlists
e.g. shuffle songs from playlist 'elektroNOW' with songs of playlist 'Are & Be'.
2. Make it possible that the Library has its own playlists "most recent", "most popular"
e.g. most played songs by you this month, these 6 months, this year etc
3. Make it possible to see which songs are newly added to a playlist by placing them on top of the playlist.
e.g. playlist 'elektroNOW' has 5 new songs.