I have just returned from 3 nights at the Picadilly and have to say it is a very comfortable and well located tourist hotel. It is located no more than 5-10 minutes from San Giovanni metro station on the very busy Via Magna Grecia. The area feels very safe as the vast majority of residents are local, I could not see any other hotels in the area.
The room is functional and clean, they are in the process of refurbishing the hotel, the room had all the amenities you would expect, a decent bathroom, towels are provided, TV, mini bar. The windows are double glazed which allowed a good night's sleep. The Via Magna Grecia is a busy and noisy road (even at night) why do the Italians love their car horns so much. The only slight downside was the lift, very slow and at breakfast time it took what seemed like ages to arrive at your floor empty, as it only takes 3 people.
Breakfast is in a 8th floor dining room with a great view over the city, you can just about make out the top of the Colosseum and St Peters is clearly visible. The buffet breakfast offers a good variety of options, I found the scrammbled eggs and bacon very good.
If you need to temporarily stow your luggage after checking out there is a free room available for the purpose.
We found the staff fantastic, they all spoke very good English and were most helpful especially when explaining the excellent public transport to us. Bus 87 stops directly opposite and takes you to the Colosseum and terminates not too far a walk from the Vatican, the 360 takes you to Termini railway station. They did recomend a restaurant, its menu being displayed in reception, best avoided, we found it poor in all aspects. I can thopugh highly recomend 'l Corsari' ,turn right from the main doors and the restaurant is on the other side of the road about 100 yards away. We ate there twice, the quality is excellent and the waiting staff are very hellpful, the restaurant is frequented mainly by the locals so the prices aren't a rip-off.
All in all we found it a perfect base to see the sites, the traffic noise is the only consideration - maybe a room on the opposite side to the Via Magna Grecia would be quieter. Thanks to the wonderful staff the Hotel Picadilly is a great place to stay.