Honestly, for a casual home setup, it goes well beyond what anyone needs. You can configure it to the n-th degree. It supports pro-level PTZ security cams (some of those cameras are expensive af). It has options for triggering based on hardware interrupts (monitoring serial ports, ethernet packets, whatever you want). It can trigger external alarms itself (with addition hardware). It uses computer vision techniques.

In short - it is basically a professional video security package. There are companies out there that package it up (video security appliances) and sell it as such. Again - waaay overkill for most people's needs.

But it isn't very difficult to get set up and running, provided you have the right hardware. For instance, at home I run it using an old 900 MHz P3 with 512 MB and an old hard drive; it supports a couple of cameras easily - I could probably add one or two more streams and still be ok. Beyond that, though, you'd want to increase the CPU and RAM (something I plan to do is break out an old Core2Duo and repurpose it for this job).

I use cheap IP cameras for my cams, but ZM supports a wide variety of cameras (everything from video capture boards, to webcams, ethernet/wifi IP cams, etc). It can upload captured images and videos to servers of your choice, email them to you, there's a android phone app available...