Massimo's place was a fantastic stay.
The area in general is great, plenty of shops on the street, a cafè basically next door that was perfect for coffee and croissants for breakfast. There is a tobacconist across the road where you can buy bus/metro tickets. Good restaurants within short walking distances. The Colosseum is about a 15 minute walk. If you enjoy walking, you can continue that direction on towards the Trevi fountain, Spanish steps, Pantheon etc which are all approximately 15-20 minutes further walks each stop. Alternatively you can get the 81 bus which Massimo recommended. Apartment is about 15 mins on the bus from Termini. There is a 24hr supermarket literally 3 mins around the corner.
Area felt absolutely safe for us, had no qualms about walking around day or night. The restaurants and cafès were mainly dined in by locals and I can't stress enough how much this added to the proper Italian feel and how much cheaper it was compared to the more touristy places. I did use it as a chance to work on my basic Italian but someone tended to speak some English too.
The room itself was spacious, very clean and the bed was very comfortable. Shower was excellent, always hot water.
As a host, Massimo was excellent. On day of arrival he emailed us maps with the local supermarket and advice on transport. Was very accommodating with our slightly earlier arrival. He gave us plenty advice regarding sights, eating out and directions. He is very fast at replying to emails. Although we only seen Massimo on the first day, that is because we are very independent travellers and we had no issues, but he made it very clear not to hesitate to contact him for anything and I've no doubts he would have sorted it immediately.
Overall, it had absolutely everything you could ask for when travelling and I couldn't recommend it highly enough to visit a wonderful city.