The people that complain about the cost of Spotify are the same ones that give one-star reviews on app stores bitching about the £0.69 cost.
From a consumer’s perspective Spotify is amazing.
No need to buy more storage, wide library and you can use it everywhere if you use offline mode. I really do think it’s the future. It is like having an unlimited card at blockbuster or a library card, did libraries killed publishing? Did the VHS killed cinema? Did the DVD killed cinema? No, it didn’t, format is not the same as the need for a content. Movie studios adapted to that and labels will too. I really dislike buying online music, if there is something that I really like I go buy a record not an MP3/WAV file. I wish that we will see more and more streaming services implemented on Traktor and Serato once some kinks are ironed (High quality streaming). The new computers are not really suited to carry giant TB’s collection (no 2nd drive anymore in MBP) and taking an external HD with you is not very practical. Being able to listen to anything at (almost) anytime in 320 is liberating.
For smaller devices it is even better - Traktor DJ is fun for house parties but again you have the chore of storage, download etc. I tried the free Pacemaker app, it has flaws (mono out when split, no airplay) but it is brilliant for everybody, a portable turntable with unlimited library and no storage issues.
NI and Serato should seriously consider a deal with Spotify. The con’s are quality of the file (it sure can be worked out), online access (if you have an issue - just use backup of a small HD) and the classic rant of labels (come on if everybody is on spotify it will level the playing field, iTunes store did not kill them and more customers would be inclined to buy real records with nice covers and extras).