I’ve have had a look at it in the past and as much as I like the design of the thing, unless you’re really buy into the ecosystem, it seems very expensive considering that the thermostat by itself is not actually wireless to your boiler, only to the internet bridge.
With the nest being ~£199 all in, the comparable option from Tado seems to be £278 (starter kit plus the extension kit to make it wireless and control the hot water).
I do really like the fact it can be completely wireless though. With all of the complexity of the Nest, as much as you can remove the power supply and it’ll work for a while off the internal battery, it complains quite quickly, requiring you to plug it back into the mains to use it.
I put some thoughts on smart thermostats (specifically the Nest but applies to all) in this thread if you’re interested.
Presuming you had a properly set up timed thermostat in the past, I wouldn’t imagine you’ll get any savings from the system, but you will likely appreciate its smartness and the ability to more easily make your house the temperature you want it, when you want it.
Interestingly, if you bought the Tado from them directly (or specific other retailers), you can return it up to 12 months after the purchase date if you’re not happy (they don’t require any bill information, just that you don’t think it’s saving you money).
If you have a house where a number of rooms are not often used and you add the smart TRVs to the system, I suspect you would see savings there, but if you’ve not got a modern well insulated and correctly ventilated house, you might also end up with bigger problems of damp/mould in those colder rooms.