I had Sprint as a local phone company and DSL ISP in the early to mid-2000s. The other options in this small town were cable, but with a dial-up uplink or Hughes satellite.
Sprint was a great ISP, downtime was perhaps two times over the years. CenturyLink purchased the phone and DSL from Sprint, and coasted along on Sprint's old infrastructure for a about a year then the bandwidth exhaustion set it. First it was the peak times that were unusable, then it was just about anytime day or night that latency was through the roof. Fixing it was just around the corner. When I switched to cable, it took another 2-3 years to resolve it.
Edit: I'm not affiliated in any way.
The speeds are great, the uptime (excetions noted) great... They seem to have some serious logistical issues, but the internet connection itself has been good. 120mb down, around 22mb up.
CenturyLink doesn't serve my home with anything better than 6/1 service otherwise I'd use them. Thank god for regional monopolies.
I only switched to Comcast at home last year because it was 2013 and 1Mbit upload speeds for the price I was paying was ridiculous. At least with Comcast I know how to play the "the cost is too high, do you have any special offers this month?" game. They've been just as consistent, without the physical disconnects.
Basically like any megaprovider, they only do as much as competition forces them to.