very good ‘soft’ primer on the Waves site: Ambisonics Explained: A Guide for Sound Engineers - Waves Audio
in short, one mic, allowing for virtually any mic pattern, and which produces an image that can be mono/stereo/MS/quad/5.1/cube/sphere etc. etc. the image can also be processed in various ways while you mix, i.e. tilt, roll, rotate, focus. Using so-called hybrid mixing techniques you can combine multiple image types to build a complex sound stage. Also, ambisonics can be manipulated ‘live,’ where your project stays open, i.e. not ‘baked,’ so you encode/decode in real-time to whatever array has been specified.
I fail to see how this isn’t ‘awesome’ relative to working with mono/stereo/[insert brand name] surround formats. 