I've tried it close to the first rad on the system set high, and last rad in the conservatory. Either position overshoots. and then takes a while to drop and it's during this period can feel cool. Apparently Hive does not have TPI which most cheaper thermostats have (apparently stops burning gas as it approaches target temp to see if it temp continues to rise, but the keeps burning small amounts to keep as close to target). There's a massive thread on Hives website relating to this issue
If you're house is feeling cold surely that would suggest you've got the thermostat in the wrong place? Try moving it.
Depends what you have now. If you have the traditional ancient setup of a mechanical room thermostat and a separate time controller, putting control of both time and temperature into a single programmable device has benefits - such as being able to set different temperatures at different times of day. But you can achieve this with a £30 programmable room thermostat. Having it connected to the internet is useful if you go away, so you can switch it off while you're away and have it back on for when you return. I'm not sure if the Hive does this, but the Nest has a feature where it monitors how long it takes your heating to work and also checks the current weather outside and adjusts the time for starting the heating accordingly - i.e. if you want it at 22 degrees for 7am then it might turn the heating on at 6am if it's a particularly cold morning, or 6:30am if it's not.
I managed to get the fully installed option + kit for a total of £151 during a recent eBay 20% promotion. I swithered about self install but with an older Ideal ISAR boiler I thought it worthwhile paying for a professional. Given it took him nearly three hours to install the kit I think that was money well spent - I suspect it would have taken me a lot longer!
I admit I know next to nothing about Hive, but I'm starting to want one. We are running on an oil boiler, can I use it? I take it, it is just a remote (smart) thermostat?