Our smart meter has saved us a significant amount of money, mainly through allowing time-of-use tariffs.
A few years ago our daily routine saw us using very little power in the peak hours of 4-7pm, so a TOU tariff that was more expensive when we weren't using power but cheaper when we were took a decent chunk out of our bills.
Then we bought an EV, and this is where it took off. We moved to the Octopus Go tariff, which means normal prices most of the day but 5p/kwh for four hours, normally overnight; running the dishwasher and charging the car during these times slashed our bills enormously compared with what they would have been otherwise.
Now we are on an experimental tariff called Octopus Go Faster, which shifts the cheap period to 8:30pm - 12:30am, so we're able to charge the car, do washing, run the dishwasher and often cook dinner all during the cheap period. We don't use much electricity at other times, so overall the average cost of a unit is about half of what it would be. As this is an experimental tariff they also give us £5 a month back for reasons I don't understand but am happy to live with :-)
The other month they even paid us to use electricity for a couple of hours on a Sunday morning. I imagine the main fuse was glowing...
It is a SMETS1 meter and has no issues since fitting. The in-home display is rubbish, so we don't use it, but other than that I can't fault the meter or supplier.