Hive is just a glorified wifi timeclock, there's nothing really smart about it.
As far as I am aware "Smart" means it connects to a phone, and nothing else, however I do like the concept of the Hive system, where the TRV head sends a "demand for heat" to the wall thermostat, so while any room is under temperature the boiler will remain running, allowing the return water temperature to control boiler output, but will still auto switch off as weather gets warmer rather than have boiler cycling.
But unless the Hive TRV heads are also fitted and linked to the wall thermostat, it is rather useless.
The pictures however show up and down on the motorised valves, and there seems to be two Hive bases, which makes on think the old motorised valves are still used, this seems in most cases daft, OK my house where the flat under the house is rarely used, having a motorised valve to turn off flat makes some sense, but in the main house we have 11 radiators, want the toilet and bathroom always heated, at 8 am I want the temperature to raise in two bedrooms and kitchen, but 10 am I want the living room heated and bedroom temperature can reduce, by 3 pm want dinning room heated, by 8 pm the dinning room and kitchen can reduce heat, by 9 pm the bedrooms are heated again, by 11 pm the living room is allowed to cool, the craft room and office we press the button to change from eco to comfort when we want to use them, I am sure most homes are the same, two zones are not enough for the modern house, you want more like 8 zones, so zone valves are out, and programmable TRV heads are in. And the whole idea of Hive is using Hive TRV heads they talk to the wall thermostat.
To my mine it is a rather expensive system, at £50 per TRV head my house would cost over £500 to use Hive TRV heads, I have done it on the cheap in the main with eQ-3 heads at £15 each for blue tooth version, non blue tooth down to £10 each, but at £90 for second Hive that would have bought 2 TRV heads and with programmable TRV heads no real point in having zone valves, the TRV heads are zone valves.
I am rather disappointed, I went for MiHome and Nest, only to find Nest has stopped supporting MiHome TRV heads so now they are not linked. And Nest don't seem to do their own TRV heads, so in spite of having OpenTherm and volt free contacts Hive now in theory at least works better than Nest (assuming also fitting TRV heads) even EvoHome to connect to the ebus needs an extra module, don't know about Tado?
So yes if fitting half a system, i.e. wall thermostat without linked TRV heads Nest is far better than Hive, but if fitting complete system Hive now better than Nest since Nest removed the link with Energenie MiHome.