I can understand Spotify want to encourage users to pay for subcriptions, but for those users who can't afford a paid service, the free service provides a great service that youtube isn't comparable to.
However, having a time limit for non paying accounts means more users are more likely to breach copyright to obtain music through alternative sources.
I've in the past used internet services which have free and paid versions, but where they differ is that they still offer a BASIC level of unlimited service once subscription ends. They don't just stop working. Strange example, but I'm referring to Runescape. While it's an RPG and not comparable as a service, they instead work to offer EXTRA benefits for members while allowing poor people like me basic access for an indefiniate time period.
I really don't mind the adverts if that covers the cost of receiving the service, but please, just make sure they're not invasive, I have an anxiety disorder that's triggered by sudden noises. I want the 2009/2010? Era of spotify back. Where I could just listen without inteference.....
I look forward to hearing from you.