They have really become the gold standard in avionics, so much so that some airframes are preferred to others due to the fact that they've chosen to integrate a Garmin flight deck instead of Honeywell/Rockwell/etc. They have a very consistent and capable design methodology that extends from single engine piston avionics all the way up through relatively large GA jets.
They've also made advances with their Autoland product, which can take control of a small aircraft and safely land at an airfield while communicating with ATC.
