I gave up Sprint last month.
My experience here was spotty coverage. I had free roaming but some places ,even yards from a tower , no coverage existed.
Last November I received a courtesy call, I assume because I had yet to upgrade/renew. The rep said faster/ better (4G?) was on the way and would be in place here by years end. HA !
My bill ran $126 a month for unlimited usage on one phone. I went to Straight Talk bought one of their LG Android 4.0 phones and have no plans on looking back. 45 bucks a month unlimited on ATT network. Almost one third the cost.