Ours has worked great and has allowed us to be on a smart tariff for over a year now. We've saved well over £700 in that time over someone with a standard tariff.
Connectivity is an issue though, particularly in certain areas and in certain kinds of property, so frustrating if you want to access smart tariffs but are unable. The infrastructure needs to be improved as a matter of urgency.
A smart meter that doesn't send readings can be read exactly the same as a traditional meter and you can manually send those readings the same, so not having a smart meter isn't really that much of a 'win' as even if you did have one and it didn't send, you're not any worse off than you were before. But if you want the smart time of use tariffs, then it would be very frustrating to be unable due to connectivity.