I started using Pluto Home, the predecessor to LMCE, in late 2006. At the time I was a Linux newbie. The basic guidelines of using this system still apply to newbies, whether they be total Linux newbies, or just new to LMCE. Buy the exact hardware specified. The functions that work, work really well, once set up according to the provided instructions. Be patient, especially if you're trying to add support for unsupported hardware - in which case you may need to know a little about programming and/or databases.
What Pluto Home gave us, for free, is basically a very powerful framework. You might think of it in terms of an actual house. The roof is on and the walls are up, and you can live there using an air mattress on the floor and a toaster oven - but it's not the best-looking house, most luxurious in the world just yet. We are still trying to improve the software, so that anyone without computer experience can just 'buy the house' (install LMCE) and 'move in' (start using it with recommended hardware from a large list of widely available stuff). In the meantime, if you're a programmer, you can make it do whatever you want. And we appreciate it when people pitch in and do that. At this point, we have the most powerful home automation framework available in the world - paid or otherwise. It just happens to by very DIY at this time, just as Ubuntu was very DIY a few years ago. In a few years, when you can buy an Ethernet port or wi-fi as an option on everything in your home from an oven to a bathtub, LMCE will be immediately ready to support it, at a lower cost-of-ownership (both short and long term) than any other system.
TV: The entertainment industry does not want *ANYONE* to have a PC-based HD PVR right now, *especially* in the US. Period. Windows and ATI showed a 'demo' model in the spring of '07, and we have yet to see it hit the shelves. The closest thing available, is a USB Hauppauge box that's component (Y-Pb-Pr) capture and about $250 US. We plan to have support for this box in 6 months, once support is added to MythTV. You would hook your cablebox up to this box, and control your cablebox using a USBUIRT. In the meantime, we have support for many of the same SD tuners, and OTA HD tuners, that are supported on other platforms. You can check the wiki or come to the chat room for more info on this. I use a Hauppauge card to record SD cable directly, and to watch my HD cablebox over SVideo through LMCE. I control the cablebox, my amp, and my TV with a USBUIRT, so that I can watch the cablebox HD directly on the TV, and still use LMCE to control everything seamlessly. All of this is well-documented in the forums, and many people in the chatroom have this setup.
Phone: You can easily flash a VOIP router, like the ones that Vonage gives away, and use PSTN with LMCE. There is plenty of information in the Asterisk forums on how to do this. LMCE wraps a lot of other projects; Asterisk is one of them. (MythTV is another.) There is plenty of support available for these projects that we wrap, both from us, and from the projects themselves. One of the regulars in the chat room runs his own VOIP company, and is happy to help with this. There are also multiple people in the chat room who have done the PSTN service by flashing a Vonage router.
Security: Pluto Home (the LMCE predecessor) built in support for basically two security panels - a specific RS-232 adapter for certain DSC panels, and a specific line of Honeywell security panels. The DSC Panel works, with some manual setup and tweaking, and you get most of the functionality available in LMCE. (It's inexpensive but requires some manual setup.) The Honeywell panel works *great*, it's totally plug and play, and you get all the functionality available, including "Entertaining" mode. (It's a fairly expensive panel.) If your panel's not supported and you are familiar with basic programming, please help us add support for it. People with only basic programming skills are adding support for their own devices every day using the GSD framework. Otherwise - yes, the consensus among our high-level developers (like TSCHAK) is that you don't really need a separate security panel. The LMCE system is much smarter than the $2000 Honeywell security system.
Home Automation: This is where 80% of LMCE's power comes from. It's about 20% Media Center, and 80% automation. Of a whole score of things - lights, home entertainment equipment, appliances, sprinklers, pool heaters, etc.
As far as KISS - I'll return to the analogy of the house. The construction of a well-made home that conserves energy, looks good, and lasts for centuries is not a simple task. LMCE will be the virtual framework for the literal 'house of tomorrow' - it will be conserving the home's energy, controlling entertainment equipment, and providing total home automation, for a low cost.
As technology controls our lives more and more, I feel that open-source becomes as important as an open judicial system - especially with something like LMCE, that can control many aspects of your home life. I like to think of the project as a virtual 'Habitat for Humanity'. Right now the home we're offering requires that you buy very specific hardware. Some day soon it will help change peoples' quality of life - by offering low-cost lighting control to people with mobility issues, amongst many other things. We need help now, and we'll need help then. If you know even a little bit about how to program, you can help build the house of tomorrow. In the meantime, if you follow the instructions, and ask for help, you can have much of the functionality that you're complaining about.