Interesting and empty!
Especially when combined with a visit to the Protestant (and general non-Catholic) cemetary, bizarre pyramid of Cestius, Porto San Paulo and Aurelian wall at Pyrimidae, this museum makes a trip to the southern edge of the city very worthwhile.
The museum is the overflow of the Capitoline museum, but houses some very interesting and beautiful pieces.
The collection is mainly sculpture, displayed against a backdrop of industrial machinery; a faint smell of diesel and engine oil lingers in the airy turbine hall.
My favorite items were the 'Statue Of A Muse; Polymnia' and the two staues of Pothos in the Boiler Room, and the mosaics and litters at the back of the Hall of the Columns.
When my father and I visited (on a Friday morning in May, we saw two other visitors; a delightful contrast to many of Rome's exhibits.
If you come in the morning, we would also recommend luching at a delightful place on the Via Ostiense, Ristorant Trattoria Vechi Mercati; local feel, good, fresh food, and amazingly good value!