Pisa is best known for the world famous Leaning Tower, but those who come here with their mind already made up that the Tower is the only thing to see may miss the rest of the architectural and artistic marvels of this beautiful city.
Pisa would not be Pisa without the University. The city is animated by the students, who organize parties, shows, and cultural events, and fill the central street of the city at night. The University of Pisa has 60,000 students in a city of about 100,000 inhabitants. You'll notice the student flair in the city once you leave the touristy campo dei miracoli.
Pisa is a safe city, you do not need to worry about your safety (except for some zone at night, such as the area surrounding the station). However you should take the obvious precautions (like, if you stay in a very cheap hotel, take your valuables with you) and watch out for pickpockets in the touristy areas.