Great location - you will have enough time to admire Coliseum during your stay :)
Flat itself is large enough for 4 people, for couple you will get extra room for dining or breakfast.bathroom at main bedroom is w/o curtains so you will get new experience in a shower :)

downstairs there 24/7 Carrefour shop also some touristic restaurants.
metro station 5min walk away, everything else is about 20-30min walk by foot. (exep. Vatican, you should probably go there either metro or bus )