A first flight in a Comanche is not a good way to demonstrate instructor competency. It is fairly complex for a single engine. I would not chose it for instruction unless the student owned one or was contemplating purchasing one. If it is the only complex aircraft this flight school has on the line, I would consider another job. If you do decide to go for it, try to download an aircraft manual and get familiar with the systems, especially the fuel system and gear.
Having said all that, I must say that I have enjoyed flying the Comanche. It is fast, efficient, and handles very nicely. It is also old, and unless meticulously maintained, it is unlikely to be reliable.
Joe