I realize that I don't post a lot, but I feel... Strongly about sprint. At least for my area, it is probably the worst carrier overall..
I usually take a few things into consideration. 1) can I make phone calls? 2) can I receive phone calls? 3) if I need to look something up, can it be done in a reasonable amount of time? I'm not saying lightning speed, but 30 seconds to load the mobile version of CNN's homepage is excessive.
To the first point, for years, the first two were always reliable. Always. I knew that I would never worry about an emergency. Originally, Alltel, Sprint, and two local carriers were the only service providers (T-Mobile had a minor "presence"). Sprint was considered the premiere wireless provider. Data was useless, but back then few people had wireless data. In 2010, for a few months, 3G came and was respectable at 100-300 Kbps. Over this time, ATT and Verizon both came to our market and created 4G expansive coverage. Sprint is still on 3G....
This wouldn't be a proble, but call quality dropped. Calls started being missed and not received. Rarely, maybe a call failure. I've moved to a larger city and I have LTE now.. Sometimes if I'm at the right place. In my apartment on the third story near a window, I have 1-2 bars of regular service... That is not reliable. I have missed more calls here. It's also taken over a day for me to receive a notification that I have a voicemail. Most calls from here succeed, however.
My disenfranchisement comes from when I'm attempting to return home. The roads I take are small and not well traveled. For over 60 miles of sprint service, I could not make a single phone call or receive a phone call. Many were simply call failures where the phone did not attempt to dial. Sometimes I would get an instant busy signal (to a cell phone with voicemail service) after it took 20+ seconds attempting to connect. I work night shift, so I travel at nights. At 3-4 am on a deserted highway where your cell phone has service but won't call... Is unacceptable. I could have been dying and attempting to call 911. This would have been impossible for me, and there are few if any cars. Even a mile is unacceptable, but 60??? That's ridiculous.
On occasion that I would dip and fall out of sprint service and roam onto Verizon, I would receive a message that the number I'm attempting to dial is no longer in service or has been disconnected. I didn't try 911 for those portions as there was no need, but I still should have been able to make the phone call... I'm not sure if this was an error on Sprints side or Verizon's or possibly my phone (iPhone 6 Plus). The call failure is my single largest complaint because that can be life or death.
The calls not coming through or registering all of the time is frustrating as well.. I am rarely on call, but when/if I am, and I am called, I have a legal responsibility to answer and come in. I can be charged with a felony for failing to do so. Fortunately the usually call multiple times or attempting emai, and text messages.
With these issues that are relatively new, I cannot recommend sprint /in my area/. Even if the data did not work or calls did not always come in, I could at least have recommended in the past that your life won't be in danger in an area that you supposedly have coverage. That's the single most important part.
With ATT and Verizon now in our market, I have never heard a recommendation for sprint. They are last line. They are the cheapest, but it's still questionable to me. Usually, that's the only positive I can give.
Traveling wise, I usually don't have many issues. For example, in 2010 I attended a conference in Anaheim at the large convention center. While I could not access data, I could make phone calls and send/receive texts. Others, even with Verizon, were unable to do any of those things. I also had an Evo 4G and I could use WiMAX in a small "open" area of the building that was quasi outside. I may be getting my timeline mixed up and confused, however. I attended another conference in 2011 at the same convention center using a Samsung Galaxy S2.
I also remember being in Seattle and using my phone for navigation in 2010 or 2011. It was very helpful. Maybe larger cities are having less issues than my rural area.