Whether or not they are "excellent" may depend on what you're trying to achieve. Yes, devices such as Hive and Nest might do what they do very well, but I can't help thinking that reviewers may be judging them on that, rather than on what users actually want them to do.
We had our house substantially rebuilt this year (extended, re-wired, re-plumbed, etc) and I wanted a smart controller for the heating system. I really did. I spent a lot of time looking at the various options on the market but in the end I decided not to bother. They all seemed to have too many drawbacks for my expected real-world use.
For example some devices such as Hive use geolocation so that they can detect when you're away from home. But if your mobile phone signal is a bit flaky where you live, the system might decide that you're out when actually you're in. If there is more than one person in the house, you need to make sure the geolocation can be set up on everybody's phones and that you can do that without having to share accounts and passwords. And if the nature of your employment means that you travel around and sometimes pass close to your home, then the system might think you're coming home and switch itself on when in fact you're just travelling from A to B not home.
By contrast Nest doesn't do geolocation but has a sensor to detect when the house is occupied. But that has its own problems. The best site for the thing to detect your presence may not be the best site for it to manage the temperature of the house as whole. Then you have the whole issue of multi-zone controllers and how they relate to one another. And then you have the conflict between the system learning how long it takes to warm up the house so that it's warm when you get in, versus the system detecting when you're in and out and not switching on until you're in.
My conclusion was that these things works best for small single-person households, but don't necessarily work so well for family homes.
I think what I'm saying is that you should think through what you actually want to achieve by way of controlling your system, then check your list against the functionality of the different devices on the market, and only then ask for opinions as to how good they are at delivering the functionality you want. The advertising (eg "control your home from your phone") may be seductive, but it might not be what you want/need.
