The two GTN units (the larger 750 and the smaller 650 below it) have been upgraded to their newer Xi versions which are faster, and have an even better screen resolution. The bezel design to hold on to in bumpy conditions has slightly changed, and Garmin moved the HOME button closer to the Direct-To button.
Make use of the free Garmin training simulators for iPad or PC and of course RTFM – Read the flight manuals – the Pilot’s Guide (copy the PDF to your EFB – the hardcopy MUST ALWAYS be left in the aircraft!) and the AFMS to familiarize yourself with the software.
Functionality and design of the software are by and large identical to the devices you have experienced so far.
There are still some minor issues to sort out – at the moment VCALC has to be enabled and VNAV is not; we will address that in the not so distant future -, but the units are generally working just fine.
Enjoy the speed difference!