Since the Italians lacked a tried and tested carrier aircraft, nor had any way of buying them from someone else (the Germans didn't either, Japan wasn't really in a position to send any, and the other carrier powers... yeah, no), she was a nice idea that had no chance of being a realistic combatant. She'd have had a small air group of questionable-value planes, and would have needed to rely heavily on air support from land bases- so why bother with a carrier in the first place?
As DoctorMonkey said, the Graf Zeppelin would have been a much more effective ship if she'd reached service- even then, the trial and error approach to learning to run carriers that the British, Americans, and Japanese had wasn't available to the Germans, who would have been stuck with learning on the fly- literally, a 'crash course' in CV operations.