The quickest answer is that yes, you need to visit Transylvania. It is one of the best part of Romania to see, beyond the fact that it has a lot of old styles of fortresses, but it also has some impressive parks and history to complement the rest of your tours within Romania or even the rest of Europe.
When you go to Transylvania, there are possibly three places which you need to visit to develop a wonderful appreciation of the land: Bran Castle, Sibiu and Alba Iluia.
|Bran Castkle the home of Dracula in the novel Dracula and Queen Marie of Romania|
|Sibui-- also known as Hermanstadt, which was the heart of the Transylvanian Saxon culture|
|Alba Iluia the heart of the Romanian Culture in Transylvania|
These three places will give a meaning to Transylvania that you would not get elsewhere. There are of course many other cities to visit but in my mind these are a must within this lovely land