During 2012 I gave Spotify a try to see if had become more usable, but for me the situation is still the same. A lot of missing music (and more missing for every day that passes), lacking metadata, incorrect metadata, and completly broken grouping.
Multiple artists with the same name
Artists with the same name are mashed together on the same page. Considering Spotify is working together with record labels to get their music, and not some teenager who shares his/her warez collection (at least not any longer), they really ought to have the details needed to make this distinction. Neither Wikipedia nor MusicBrainz suffer this problem. I used to have some good examples for this, but it seems like those artists have been removed from Spotify.
No distinction between different album types
A good example of this is Bob Marley & The Wailers. Take some time and open that view in the Spotify application and try to figure out which the original albums are. Done yet? Now compare the information Spotify gave you to the structured information found over at MusicBrainz. No matter how hard I try, I’m unable to understand the reasoning behind slaying the metadata the record labels must have available for Spotify to use.
No respect for original date vs release date
While you still have that Bob Marley & The Wailers view open in Spotify, and you’ve correlated the original albums from the data you found over at MusicBrainz, please try to figure out what years the original albums are from. No, Uprising isn’t from 2001, neither is Kaya.
Band members
I would be amazed if the record labels don’t have any legal relation with the bands they release albums for, and thus they most likely know which members each band has for a specific album. Heck, it’s something usually found in the booklet of CDs. This information should exist in the user interface, and it should be clickable. If I find a good artist, I want to know what part its members had in the production, and I want to know what other projects they’ve been a part of, as that might lead me to more good music. An example of what I mean, in this case Metallica - Kill ‘em All, can be found over at MusicBrainz.
Record labels
I kind of expect record labels have some kind of interest of people finding other music they’ve released so that they can squeeze out some extra cash from Spotify for additional played music, so I’m kind of baffled by the fact that it’s not possible to browse the complete catalog of some specific record label. A good example of this is Iboga Records, where if you like one artist, you probably like them all.
Cover Art
Sure, Spotify has cover art for its content, but yet again, since they’re getting their data from the record labels, they really ought to be able to provide the booklets as well. Not super disappointed that they don’t have this, but it would be a nice addition. Musicbrainz is of course on top of things here as well, see Pink Floyd - The Wall for example.