I used to have Spotify, but I prefer (and use) Google Play Music nowadays instead. It's much more flexible since I can throw stuff from my own library, such as rarities, bootlegs and stuff into the mix. Not sure if Spotify also allows that nowadays though... Anyway, I'd have no problem with such services if they were a bit more beneficial for the artists as well; then again, that would probably make the monthly subscription price to raise significantly. Hardcore fans such as we aren't really that problematic since we have bought and keep on buying records and all that, but on a bigger scale Spotify and others have definitely changed a lot in the industry.
But from a personal point of view only, I gladly pay 10€ in a month for Play Music. It's neat to have such an extensive music library with me when walking, running, driving and all that. It also makes discovering albums I'll eventually end up buying easier, but then again, when looking from a perspective of a consumer who starts out his/her personal music discovery via these services and having not grown in a world of physical format... Yeah, I can see the effect.
But it is what it is.