I haven't stayed there but booking.com rates it as a "Wonderful". As I've used that site a lot for our bookings, I tend to believe that their reviews - from which ratings are generated - are legitimate.
https://www.booking.com/hotel/it/santa-maria-roma.html
I've no idea what looks 'shabby' to you but having given a read-through of the reviews, I wouldn't have any hesitation booking this one. There are lots of comments praising the location and the staff. Was everything perfect for everyone? Is everything EVER perfect for every guest at every accommodation? I will note that beds in a fair amount of Italian hotel are stiffer than what we may be used to, although I'm not reading that as a common complaint for this hotel. You can't come to that conclusion just from photos.
Consider as well how many hours you'll be sitting in your room versus out exploring lovely Rome.
PS: We prefer tile floors to carpet as they tend to be cleaner.