This is my second time staying in this neighborhood and I absolutely love it. Great restaurants, lots to do, and a great little coffee shop (Roscioli's) right around the corner.
It's centrally located with quick access (7-10 minute walk) to the Piazza Navona, Pantheon, and Trevi Fountain. The Colosseum and Vatican City are each a 30 minute walk (in opposite directions), but there's a taxi stand a few minutes away along the VEII.