We have been using it for the past few years. They use the Sprint network, so no issues with reliability.
We have found we save money - we buy used phones, we have a landline and mostly use our phones on WiFi so we don't need huge amounts of calls/texts/data per month and we usually end up in the lowest or next lowest bracket each month.

I am thinking of ditching AT&T and want to move to a less costly but reliable provider. Does anyone have experience with Ting?