The original smart meters were smet1 and became dumb if you changed providers but all newly installed ones are smet2 and can change with you.
If you forget to read your meter or struggle to access it to do that they're great. So if your meter is high up a wall and you need a ladder but aren't steady on your feet for instance.
The electricity network needs to match supply and demand as closely as possible, so smart meters help them do that cos that as they can see usage nearer to real time, this benefits us all as we work towards more renewable energy to supply....
In turn, to help level out peaks and troughs the energy companies are starting to, and will provide more in future, tariffs which reward off peak usage, so if your lifestyle allows for off peak usage having a smart meter will allow you to benefit from those (currently dumb meter customers can but only on economy 7 which is just a night/ day difference) smart meters can have more options. I. E octopus go tariff gives really cheap energy between 12pm and 4am (aimed at people charging their ev)
The smart meter network which allows the meters to talk to the energy companies is encrypted and protected in law (bit like how radio frequencies for police and air traffic control are). The smart meter does not use your home wifi either to connect to the energy company or to update the in home display. The in home display is updated by the meter using specific radio signal, it is a similar wave length to wifi but different so no clash and no greater risk to health than your wifi. So Internet coverage problems does not indicate you can't have a smart meter.
In much of the country the smart meter transmits to the energy company via sim card on dedicated network (mentioned above) but in rural North it uses radio waves (dedicated wavelength again), in theory 1% of the population aren't covered but we find rural Cumbria (on the radio version) with its deep valleys etc is much higher than that.
We are also finding that if you struggle to keep up with your bills and have a smart meter the energy companies can easily switch you to pre-payment and do more readily than they are supposed to. They are supposed to work with you and give you time to turn things round and consult you, in practice they are to quick to press the button. Then you're on pre-payment and struggling more. 😡
Do it's a mixed picture, for many they're great save you remembering to submit a reading and giving you access to better rates (if your usage suits an difference pattern) but not necessarily a great idea for everyone if you're in a mountainous rural area or at risk of not keeping up with your bills.