I've had a Skype account for years, but stopped using it when they arbitrarily zeroed my remaining credit because I hadn't used it for a while.
Looking to the future, now most mobile contracts offer free calls to land lines and IM apps provide perfectly good video messaging, Skype only remains useful for making international calls - and once the telcos move to further reduce costs in that area, MS will discover that they've bought themselves a very expensive turkey.