From the sound of other reviews, it sounds like the Hotel dei Quiriti Suite is a bit of a lottery for whether or not you will have a good experience. I stayed here for 3 nights in August, traveling solo. I should mention that this hotel is located inside a building with several different hotels/apartments, so it was a little difficult finding the check-in location, which is through one of the glass doors on the first floor (or second floor, if you're American).
The location was great, just a short walk away from two metro stations, or a medium walk away from the Vatican and Castel Sant'Angelo. There was even a great pizza al taglio spot next to the Ottaviano metro station that I visited multiple times.
The room itself was quite big, but the amenities were subpar. The shower head needed a balancing act to use properly, the shower gel unsatisfactory, and the air conditioning unit only made a small difference. The queen-sized bed was just two twin beds pushed together, and I was only given two thin sheets, no comforter or duvet. The room also had a small sofa near the door, which was a nice addition.
Overall, I think this hotel was fine for a solo traveler on a short stay. If I visited Rome again, I would likely look elsewhere, and I have a hard time recommending this hotel to others. If you are looking to save money and are willing to roll the dice on a boutique hotel with mixed reviews, then the Hotel dei Quiriti Suites will fit your needs.