What a wonderful, wonderful place to stay. A nice, roomy, clean and well furnished apartment in an absolutely amazing location. Easy walking distance from a lot of main sights, not just the colloseum (which you can see from the window!)
Big plus, the apartment is very quiet (for Rome). Obviously you're going to hear something, but much, much less than what you would expect in the center of Rome. Also, the double gates downstairs and the thick door on the 2nd floor (US 3rd) makes you and your belongings feel extremely safe.
Perfect place, if we're ever in Rome again, we'll definitely want to come back here.