I've had service with them for going on 5 years or so, now. In general, the actual phone service has been pretty good. The customer service has always been really annoying, involving half hour waits and dealing with idiots.
But I'm absolutely amazed at how horrible they are with their website.
To put it simply, http://www.sprintpcs.com sucks. It sucks horribly. I've never seen a website backed by as big a company as Sprint that has so many freaking problems. I would hazard a guess that about 75% of the times that I've tried to access it, there has been some sort of problem. And usually it's a major problem. Heck, most of the time the problem is either a server error preventing access entirely, or it's a message on the site saying that the site is down for maintenance.
What the hell?
Did I mention that I absolutely refuse to pay my PCS bill on their website because they managed to screw up my credit card payments three times there? (That's without even getting into the number of times I tried to pay my bill there and found some sort of website error, back before I realized that even if I was able to make my payment there, they'd screw it up.)
Sometimes I swear they're pushing me away, like they want me to dump their service and go somewhere else. One of these days, I think I'll take 'em up on it.