I enjoy playing CV's, however it is a steep step to be able to afford first one. If I remember correctly, I had to start with few destroyers, and build up experience/credits over three or four ships before I can buy first Japanese CV. Most people wouldn't bother.
I disagree that a single CV can change 80% of the game play, as airplanes are slow, and 2-3 enemy ships is average what one skilled CV can sink in a single game.
Biggest problem I have is the encounter with enemy fighters, as their strength seems to be very disproportionate.