We loved this flat. It's beautiful and cool, with stylish decor and super-high ceilings. We didn't realise it had air conditioning, but I am fairly certain it does. We just opened the windows and slept well, but only because it was a rainy, cooler night in Rome. I think you'd want the air conditioner normally, so it's a great amenity to have.
The flat was small but perfect. The only complaint I have is that the bathroom is a wet room, which I hate, but that's a personal preference. Honestly, the rest of the flat was so cute that the bathroom was a minor issue in my opinion.
The area is not the nicest for sure, but it's really convenient. It's a 10 minute walk to the train station and only 15 to the colosseum, etc. For us it was a perfect base for us to see the city for the time we were there and to get to the train when we needed to.
We were only there for a night, but Frank came to meet us and was so nice and helpful. He had fabulous restaurant suggestions, especially the gelateria he directed us to (in the guidebook). We enjoyed it!