"Princess Leia" hair

We watched the original Star Wars trilogy films over Easter. First time the girls had seen it, and a long time since I had.  The girls loved it, Rosie pronouncing it the best film she's ever seen.

 J gave the girls Princess Leia hair for the last film.

...now is the new Star Wars film too old for a 6 & 7 year old? and is the prequel trilogy worth watching?