Advantages:
Lovely flat in a few minutes walk to Vatican, location is REALLY good. Only one room (no problem for us), small kitchen, bathroom. They're using water heater - in case if there are more than 2 persons that can be annoying to wait for a hot water, but for us was ok. Carefour express market is not far from the appartments (about 7-10 minutes of slow walk), not bad restaurant is around the corner.
Disadvantages (possibly just our bad luck - so just fact):
Misunderstanding with owner - we dealt for a transfer from Fiumichino airport, but the time we arrived there was no transfer for us. I called Valerio and he told that I've sent incorrect flight number - by viber after registration I've sent "W6 8055" (from Vilnus, arriving at 18.30), when I was asked for a flight number again via sms - I wrote "fn 8055" ("flight number", I thought that is clear - my mistake, should wrote it fully). Any case, time, numbers and departure place remained same, and we came in time - thought I was tould that driver was "confused" about first two letters (FN in place of W6) and already left the airport (come on, even before confirmed 18.30?). Later we found out that drivers usually pay for airport entrance, so it is not profitable for them to leave without passengers - so the question is - was the drived at the airport at all? Bad start.
Next step was to take a taxi - sure it was our problem, that the driver left us next to building 690 instead of 79 (though we were for the first time in Rome so we did not know were to go and if the address is correct) saying our building is "next door" - and we had to walk to the appartments about 1 hour (by the way during that walk I've hurt my leg - and appartments' owner knew that) and pay extra for the late check in, as the owner said we could take another taxi... Sure. But yet it was our first big - and really bad - impression from the Great City - non-keeping-promises people, dishonest taxi drivers, dark roads without good sidewalk, sprained ankle, late check in and no even "how-are-you" or another word from the flat owners during all our week of staying there. Sad.
Conclusion:
In general I would recommend this place - only because of its location. It is easy to get there from Termini using direct 64 bus till Vatican and then walk about 5 minutes (bus 46 routes not so often and of course it is not going to/from Termini). But be sure you are giving full information without any abbreviations to the owners in case of transfer - or that taxi took you to a correct place (check building numbers!) Stay safe and travel with pleasure!