I stayed at Coan's place for about 4 days at the end of June with my boyfriend. The place is absolutely perfect for a couple, very romantic, pretty, clean and functional. We really took advantage of the great terrace and enjoyed a couple of dinners/ aperitivo there. There is AC in the apartment which was great considering how hot and humid the weather was.
The apartment is surrounded by shops and grocery stores open until late in the evening so it was easy to stock up. The location is great, close to Termini station but still in a very good area: we came back late at night (around 2 am) and we didn't feel unsafe. I think it would be also fine for a single woman to walk on her own.
From there you can walk easily to all the main city attractions (Trevi fountain, pantheon, colosseum, Spanish square) and grab a bus or metro to reach Vatican city.