This place is a great find! It's on via dei coronari which is a mostly pedestrian road that is literally centuries old. It is lined with cafes, shops, antiques, gelato, etc. The taxi can drop you off at the sister hotel which is less than 1 minute walk away and is on a larger road that cars can actually get to. You have to go to the sister hotel anyway for check in, check out, breakfast, and luggage storage, so it's not a big deal. The location is a 5 minute walk from Pantheon, 10 minute walk from Castel Sant'Angelo, 30 minute from Vatican.
Ok, so on to the room itself. We booked a quad room for two people, and this is what I suggest you do too. The room is gigantic for two people, but would be quite small for four. The quad room has one large bed and two pull out sofas. It would probably be comfortable enough for three. The walls are lined with bold wallpaper and large paintings of a classical style. I wish there was a little more lighting in the room, but it was fine. I also wish the bathroom shower was larger, but small showers are a common problem in Europe, so I don't think this was particularly unusual.
The included breakfast is spectacular. you get focaccia with pizza sauce, rolls, meats, cheese, yogurt, cereal, pastries, croissants, capuccino, espresso. It is quite an extensive buffet.
When I come back to Rome, I'll stay here again.