I have never been but the mountains (Piatra Craiului) are supposed to be great. A few of my friends have gone there to hike and ski and loved it. Here is a photo of the countryside from Marek Wagner for the Czech travel mag Koktejl.
Romania and Bulgaria are the new hot places to travel in Europe. Adventure travelers fear that the EU membership will make them lose their edge. Real estate agents are buying property there like crazy because it’s still cheap but they know when those budget airlines start offloading (first students, bachelor party types, then families from Western Europe) by the thousands, it is officially over.