Now that you're familiar with the general home automation scene (read that first if you haven't) we can talk specifics. Like the Control4 system.
Control4 is a more entry-level solution to home automation, and they compete mostly with Crestron's Prodigy line, which is also targeted towards lower-budget installs. "Lower budget" is a relative term, obviously, since the starter system I reviewed goes for about $US5000, including cost of installation.
This is how it works.
The brains is a Home Controller HC-300C (or HC-200B, which is simpler, doesn't come with a remote, and handles fewer components). This is what talks to all your light switches, thermostats, security systems and AV-controllers. It is also aware of events from sensors, so when, say, when a door has been opened, it will turn on your lights for that room. Everything talks over Zigbee, which is one of the wireless protocols that various manufacturers use to have their stuff talk with other company's gear.
The whole setup took about two days with two people to install, including customisation and bug-fixing. It's pretty much impossible to do by yourself - the lights and such can - but you need stuff like dealer's licences and familiarity with their software, as well as the ability to debug various components and talk to Control4 in the process. In short, it's fairly hard to get it running perfectly by yourself.
Beyond the simple setup I have, it's possible to get Control4 branded AV products like receivers, amplifiers, tuners and speakers and touchscreens that you can mount on walls and surfaces in your home to control things, and power adapters, so you can turn on and off anything that's plugged into a wall.
Here's what I love the most. I love turning off all my lights everywhere in the house, from bed, because I forgot to get them earlier as I was coming upstairs. I love knowing, from my phone, that my garage door is open - and then closing it. I love pressing a button as I leave the house and having my AC system shut off, my lights all cut and my alarm system arm itself. I love coming home and, with just one button, turning on the appropriate lights and setting the TV to "watch TiVo mode". I love turning on the heat while I'm on the toilet. Oh, and I love being at my desk and using my web browser to mess with the lights, TV, AC or anything else, without having to get up. I love being lazy. And I love being aware of what my house is doing, even when I'm not in it.
I love the customisation. Control4, because it's still installed by professionals, will be configured for your house and your setup, meaning it doesn't really matter which components you have for your TV/stereo setup - they can make it work. And in less time than it would take you, since they've done this before. Plus, it will work together with all your other components. If that involves writing specific drivers for their software to talk to your random region-free DVD player through its IR port, then so be it. You'll just have to pay a little extra for their time. And of course, once again, it's nice that I didn't have to do any of this myself.
Everything in your home can, theoretically, talk to everything else. So in a hypothetical, "all out" installation, you can tie every electronic component together. If someone triggers a motion camera outside, it can flash your indoor lights on and off, then play back a recording, like, "visitor detected" over your speakers that you have in each room. You can program in various scenarios, like setting your AV system to Blu-ray mode, turning off all the lights, turning on your intruder alarm and setting your air conditioning to 69 degrees, all with one button. Really, any configuration of on/off that you can imagine for any activity can be programmed in.
To be honest, there's very little that I'm dissatisfied with in the Control 4 setup. My setup was very basic and covered the main categories: Lighting, AV, HVAC and security. If you want to get more complicated, you can automate pretty much anything, from remote gateways and security cameras to window shades and intercoms and speakers and home audio. Almost anything a rich man can install into his house can be tied into Control4's system.
The only major downside is the price. My fairly basic install will cost $US4000ish, with an additional $US2000 installation fee for two people to come out. I could have easily cut the price of the components down to $US3000 without the garage door sensor/trigger and taking out some of the light switches that control six things at once. Then down to the low $US2000s if you forego some fancier integration with the security system. This is prohibitively expensive for a lot of people, which means home automation isn't quite there that it's viable for everybody. It's definitely still a luxury.
Slightly pricey, but worth it. As I said in the home automation overview, sophisticated home automation is coming down in price, but it's still not at the point where you can pick up a bunch of components and get everything working in an afternoon, by yourself.
That said, there's very little in Control 4's setup that I find wanting. Sure, the button-response times might be a little faster, and the price of the components and the installation might be a little lower, or the ability to tweak your setup after the install is over might be a little more robust. But the actual functionality? Can't complain. I can turn on and off my lights, AC, open my garage door, control my AV setup and see what's going on in my security system from my phone, my computer, my remote or over the internet. Hell, the system is even smart enough to know when one thing happens and do another action, all by itself. And that's the point of home automation. And that's worth it.
Think of home automation like owning a car. Sure, you can get to where you're going with a bike. You can your groceries in a backpack and walk to dinner. But once you've spent the money on a car, there's no going back. How can you give up the convenience?