About the "Playlist a whole album is too complicated"; I'm not sure what he mean by that as you click on a song in the album and it plays all the album.. this could hardly get more intuitive than this.
Of course, there's not all songs but at least they let you upload your own local music (Unlike grooveshark for instance).
Unlike the author, I really like the concept of playlist in Spotify. Basically, it's simply a list of pointers to the real song. So, basically, if you want to save the album, just create a playlist with the name of the album.. in fact, it does that for you automatically if you want.
On the negative side, as someone else pointed out, I wish they had a better "Suggesting new music". Yes, there's a radio but I feel it's not really good. They always show the same songs and most often than not they're not in my taste. I mean, I've got 1000+ songs in my playlists, I'm sure they could use those datas to guess a little better what I like.
A missing feature that I loved from grooveshark was: "Show me a playlist who contains that song". It was a nice way for me to discover new artists/songs. I'm not sure why it's not in Spotify as, unlike guessing a good songs, this is fairly straightforward to implement.
Another thing that is annoying is how the sync mode works in the desktop app. Basically, if you're in "online mode", it syncs it.. while offline don't use internet. The problem with that is sometime I want to "be online" to listen to the radio or something, but I don't want it to download all songs that need to be synced. (Say when tethering from my iPhone). Also, in the desktop app, if spotify starts when I'm not connected to internet, and then get connected, it will stay in offline mode forever.. there's no way to "turn on online mode". I have to restart the app and then it notices that I'm on internet. And yeah, same problem, since I'm on internet it will automatically start to sync everything.
And, finally, I wish it had a web interface. Yeah, we get it, with the desktop app you have more freedom to implement whatever you want. But still, a materialistic web version to listen the radio or your song might be useful..
So, in summary, it's not perfect, but it's the best solution I've found. And, it's legal :-) (Even though I had to hack the system to get it working in Canada as Spotify is illegal here.)