We went for Tado.
As Kim intimates, all the internet controlly things are a compromise and have pluses and minuses.
Our system is great - we have expanded it over the time we have had it to now control every room using wireless radiator thermostat valves; if we are only using 2 rooms, they are the only ones heated. Some rooms are on special timings; eg bathroom for the time we usually use it, bedroom just before bedtime, etc.
Coupled with the smartphone location control ability of this system (if we are both out of the house, the heating goes off; as we approach home, it goes back on before we get there), and the ability to easily set different per room programs for every day of the week if necessary, it is a very powerful system and has saved us a little money on the heating - not quite the "31%" claimed by the manufacturer; more in the region of ~15%, I reckon, looking at previous years usages.
Fitting was dead easy - take old thermostat off, wire up the new one using detailed instructions, sign up for an internet account, download phone app and off you go. On the radiators (if installed) simply unscrew the old TRV and replace with the wireless TRV (plus a readily available adaptor if the thread is non-standard) and follow the simple instructions for pairing and setup.
Pros:
Endless per room automated control if desired.
Once you have the system set up to your liking you just forget about it and let it do its job; you don't even need to touch it if you go away (location based control).
Location based control. Easy override of control manually or using mobile phone app anywhere you have signal/wifi.
Auto frost protection.
Reasonably good integration with Alexa/google/IFTTT, etc.
Auto "open window" detection - shuts off heating to room if it detects open window/outside door - reasonably reliable...
Intelligent room heating - heating does not overshoot (at least not very much); it allegedly "learns" a rooms thermal characteristics and adjusts for outside temperature to integrate heating curves.
Cons:
Needs interweb though it can easily be controlled manually if the web is down.
Batteries in thermostats last about a year and the system emails you when a battery is running low - replacement is easy; I bought cheap job lots of batteries on amazon.
Setup can be expensive if you are doing a whole (large) house (I got the basic started kit on a special offer for £125 at the time, the upstairs zone thermostat for another £100 and then each radiator for ~£60). I reckon it will pay for itself in about 2-3 years. (OvO is currently offering 20% off on Tado, apparently)
Unlike Nest, it does not "learn" your movements and setting; you manually set room/house programs to what you want and change them whenever you like (which I prefer).
Webb app not quite as nice as the phone app.
I am still waiting for Tado to implement a separate hot water control similar to their air conditioning control; our house with 2 separate pumped zones is just a little too "complicated" to allow hot water as well; I may get around to hacking a ciustom solution sometime....