The appartment is great, we didn't miss anything.
It is perfect for 3 people, as the kitchen table would be a tad too small for 4.
The beds are really comfotable, we had trouble getting up everyday as they were so good.
Location wise we didn't have any problems. The flat is a 10 to 15 min walk from Termini Station, there are Bus stops close by. We took the 492 Bus to get around, but the Colloseum is only a 30 min walk away as well. In our experience Rome is a great walking city and it feels as if you can see roman riuns at every corner.
The check in process was really easy and quick, and Amen answers really fast if there are any questions or problems.
The only negativ we had is that the shower temperature is not really consistent. But that is a really small thing in this overall perfect appartment.
I would gladly stay a second time!