I love Spotify! Thousands and thousands of songs available, all free and 100% legal. You're free to make tons of playlist, mixed songs or just one artist. And the ads? Haven't seen much of those. One picture-ad that was for a little while and one sound-ad for Snow Patrol months ago.
well i suppose you can't download the track, just listen to it.. and it takes up bandwidth or usage.. so i guess they are just doing it the way to avoid having to pay license to sell the tracks, just like a radio station