The comprehensive database in the CNX80 includes altitudes so it can provide aural callouts. Descending to an airport on an approach you get a call at 500 feet and at the missed approach point. If you're conducting an ILS approach, you'll be alerted when the localizer comes alive. With the introduction of software Version 2.0 (due this spring), the CNX80 will be capable of providing glideslope guidance for LNAV/VNAV and LPV approaches.
The transponder function is used to control a remote transponder. With the transponder key pushed, you can enter a squawk code by either using the rotating knobs or the smart key digits.
The CNX80 also features several useful timer functions, including presets for one-minute and two-minute intervals. There are also count up and count down, flight time, trip time, trip distance, flight distance timers and a trigger speed control.
As much as I like the CNX80, I do have one small nit to pick. Unless you're in the comm mode when you get a change of frequency from a controller, you first have to push the dedicated comm key before you can dial in the new frequency. If, for example, you're in the map mode and you try to dial in the frequency you'll change the scale of the map. I've found it easiest to keep the unit in the comm mode and return to the comm mode after performing other operations.
Learning to operate the CNX80 efficiently and with confidence takes some time and training. The nav, comm and transponder functions are relatively intuitive, but the flight planning function, because of its impressive capabilities, will take some dedicated effort. Pilots who are familiar with the Garmin 430/530 system say they find the CNX80 operating system difficult. I think it's not unlike the arguments between low-wing/high-wing and Mac/PC advocates. Whichever one you learn first seems preferable. But we have to expect that any advanced technology avionics will require training for a pilot to be able to take advantage of all that it has to offer and to keep its operation from being a distraction.
For pilots who were interested in the CNX80 but were unsure how Garmin's acquisition of UPS-AT would affect product support, Garmin announced that it's fully behind the CNX80, which makes me all the happier with my original choice of avionics platforms.