Silvio's place is ideal for a large group on a budget. The rental is in a historic building just a 5 minute walk from the pantheon. The unit itself is a walk-up to the first floor (approximately 20 steps). It is subdivided into two apartments that are connected by a shared entrance way. It is easy for the place to feel like one large apartment or two smaller ones by closing the doors. Each side has a kitchenette (small fridge, range stove, sink, plenty of dishware, utensils, and glasses but no spices), bathroom with a standing corner shower, a washing machine (no dryer) and two bedrooms. There is limited seating as neither apartment has a couch--only four chairs around a table to eat on each side, respectively. The amenities were not luxurious but serviceable and expected for the price.
The air conditioning was insufficient for the size of the apartment in the middle of June with 100 degree days. But, for perspective, most places had insufficient AC and the only truly cool place was the grocery store , Coop (which is also very close by and affordable). There were radiators in each apartment, but I can't comment on the heating if you plan to go during winter. My guess is that it will be sufficient.

The beat part about this place is the location. Almost everything is within walking distance: Colloseum (25 min), Vatican (35 min), Pantheon (5 min), Trevi Fountain (15 min), Piazza Navona with the Four Rivers Fountain (5 min), etc. The list goes on. Bonus content for reading my review: There is a world class tiramisu shop, Zum, just around the corner.
Silvio is very attentive and communicated easily via WhatsApp about our arrival time, arranging us a shuttle from the airport, and giving us an (extremely extensive) tour of the apartment upon arrival. The shuttle made arriving in Rome and finding his place painless.
For large groups on a budget, Silvio's place is ideal--allowing us to walk everywhere (saving money in taxis), and cook some of our meals (saving money at restaurants). We had nine people. We are close and really enjoyed our stay. I can't imagine it to accommodate more than this number comfortably.
I would recommend Silvios apartment. Five stars with caveats.