Wireless Carriers Advice?

Hi all, I've used Verizon for my mobile phone / smartphone for the entire eight years I've been in Philly. Initially it seemed like a good idea, cos I never had any dropped calls, and always had decent reception (except in that one apartment, but that probably had to do with the building itself). Now it looks like Sprint and T-mobile may have caught up, and I'd like to save some money.

Has anyone switched from Verizon to another wireless carrier? What was your experience?