I flight school has three airplanes with the G1000, and teaches a G1000 transition course. I have around 100 hours of G1000 time, with about 30 of that in a C182.
The Cessna system has some quirks, As of right now, you cannot use the audio portion of the marker beacons, due to an issue with the volume that they are set at and the chance it could cause you to miss a radio call. Also do not forget about the standby battery switch. It is very easy for someone that is not familiar with the system to leave it on which will drain the standby battery. It has a fuel totalizer that works great to give you information about your fuel range which we have found to be accurate within a tenth of a gallon, but if you do not take on full fuel, there is no way to tell the system how much fuel you have, and could cause problems. The Diamond software does not have these problems as you can use the marker beacons, you can tell the system you do not have full fuel, and the standby system functions differently.
As to flying the G1000, I was comfortable with the glass display after one flight, but it took me a couple more flights to be completly comfortable with the system. The GPS functions exactly like a Garmin 430 or 530, so if you know how to operate those GPS systems it will help alot. A couple things to remember are that an airspeed tape moves the opposite direction of the needle on an airspeed indicator. This is the thing that seems to give my students the most trouble on the first flight, and that the altitude bug is for reference only it does not tie into the KAP140 autopilot. It is a great system, and you will really enjoy flying with it. I would much rather have an airplane with a glass cockpit in IMC now that I am comfortable with it and I have flown into low IFR with both. Let me know if you have anymore questions.
