Machu Picchu is definitely worth the visit and a stunning site hidden in the deep jungle of Peru. It is a highlight of visiting the country and probably the most iconic site in South America. It takes a half day to get to it by car from Cuzco.
One can either take the all train and need to change 2 times (about 3.5 h and starts at $80 each way). The other much cheaper option is getting there by a public Mini Van from Cuzco to Ollantaytambo (about 2h) and then hike along the train to the village of Agua Calientes. It takes few hours to hike and it is a beautiful hike.
It is a great place and all, but I expected something else. What I was surprised and disappointed about is how contemporary the ruins are. They were only built in the 15th century, as a summer retreat for one of the Inca emperors.
The place is really gorgeous and worth seeing but it should not be a great wonder of the world. In comparison the Egyptian Pyramids are built some 3000 years ago and still standing! Many other world historical attractions are thousands of years old. This structure of ruins is nothing special.
