1.The ads on the free plan are obtrusive, but it's free. I didn't find them any more obtrusive than Pandora's ads. That said, I love the service and wanted to take it mobile, so I upgraded to premium, so I'm no longer hearing ads.
2.I didn't experience disappearing playlists. I'm sure this happened to you, just pointing out that it's not a super common occurrence b/c I'm on Spotify hours per day with plenty of playlists and haven't seen the issue.
3. Agreed. I miss my Beatles and Pink Floyd. However, the Stones' library is on there.
4. Again, I'm sure you're seeing this issue, but I use both Skype and Spotify on my PC fairly often and haven't had any issues.
5. In fairness, I'm just interested in a streaming music platform - not starting a movement. There are plenty of inefficiencies in the record label industry, but I'm. Just a startup guy, not an artist so it's not my fight ;-)
One issue I will add is that Spotify stopped streaming on my Droid about two weeks into my premium subscription. However, customer service couldn't have been more responsive and helped me fix the issue pronto.