I’m no advocate of the things particularly for the record. I just find it works for me. Did have teething troubles getting my E7 tariff working but sorted now.The snag seems to be that, when there have been errors, they have been consistent errors. The reported instances seem to show a problem where the meter consistently over or under reports usage, so not just the odd erroneous reading. I'm sure that they work OK for a lot of people, and if some are OK with the level of data sharing, external control of their supply, etc, and trust the suppliers etc to maintain 100% secure IT systems, then that's their choice.
The track record for ensuring adequate data security doesn't seem great, though. As these things have an inbuilt feature that allows supplies to be remotely disconnected on command then I personally would like to see a bit more evidence to show that the IT systems behind them are 100% secure.
If the meters are not reading correct that’s a “crap equipment” problem not an issue for smart meters per se. The old type meters would fail or become inaccurate eventually too. I’ve no idea of the relative reliability of each though.