I have one, works really well for me. I rarely go anywhere near the boiler. Unless you have the head unit with the temperature sensor in a warm room, I can't see why the house would take longer to heat up unless your plumber has mucked around with the boiler itself.
The old head unit when we moved in was a simple on/off timer jobbie, and a temperature controlled hive wifi unit was a lot cheaper than a wired in unit.
