I've had many people complain about their Sprint PCS service.
1. Not truly 'Nationwide', in spite of their ads. One person lost service along a major interstate once he got right outside the last major city, going to Nevada. NO service IN Nevada, at least at the time a year ago.
2. "Called dropped - Network Busy" all too frequently, even when you're not moving through the system (changing stations).
3. VERY long waits for customer service, 15-20 minutes to talk to a live person is not unusual.
4. Dead spots in the city
5. Not any more clear than regular cellular, though this may depend on the phone you get.
6. One guy had the charger burn out and get very hot.
7. Same guy, misposted payment caused service to be shut off.
8. Echos and breaking up.
9. No banking of minutes. Unless you use them ,you lose them.
I would suggest shopping carefully and asking friends a LOT. Especially taking into consideration how they use their phones, and where (hopefully you can find someone who has needs and usage similar to yours)
Try one-handed operation of the phone - some models are difficult, sometimes depending on if you are a lefty or a righty.
If you're in the city, try way in the back of the store or if possible in an elevator, bus, subway, wherever it's a test.
If you're outside the city, your performance will be very dependent on where the transmitters are (or are not) Digital (PCS), being newer, has less coverage than analog systems. Also to consider - the dual-mode phones and service, though it sounds expensive.