Everything I tell about are my personal experiences during my stay here, things might be different when you get here. The apartment is small and simple, but you have all you need for one to two persons. I stayed here for 8 nights in mid September. The two terraces are really lovely. The larger terrace had sunshine from around midday to about 18:00. You have a supermarket around the corner as well as a café (that I did not go to), a pharmacy, a bar (on the same street as Supermarket Pam, a bit higher up on the street to the left if you stand facing the supermarket doors). If you are afraid of climbing up stairs you should not book this apartment, it is on the third floor without a lift! The stairs are rather steep, too.
The neighbourhood is quiet so are the neighbours. You can walk to Trastervere Railway station, if you do not have a lot of luggage, or take a taxi (for around 10€). Be prepared to pay cash… my driver from the station did not use GPS, no cards etc. The pentry is small, and you might not want to prepare big meals simply because of lack of space to prepare. There was washing up liquid, some sugar, salt and olive oil, coffee, tea bags etc. (I guess leftovers from earlier guests). The bathroom is ok, the shower tiny (you enter in the corner and if you can squeeze yourself through an opening of about 30 cm you will be fine). Otherwise not. There are a lot of hygiene products left by earlier quests, whatever you might think about that. I did not use the washing machine because I prefer washing as I go (by hand), but the small balcony is perfect for drying clothes (bring a couple of clothes pins though!), at least if the weather is as fine as it has been for me now in September, sunshine and around 29-32 Celcius every day.
The tram 8 (or 3) are perfect to get to the center, also several buses serve from Piazza della Radio that is close, too. I did feel safe in the surroundings even as a sole female traveller at night. Be aware that the Trastevere Station has no ticket vending staff other than from 06:20 to 13:26 from Monday to Friday. There are vending machines… normally with queues!
Marco is nice, though not super talkative. PS: the front door to the building opens from inside with a white button on the wall to the left, it looks like a light switch (It took me 5 days to understand that, and not to have to use the key everytime I went out!) Everything I tell about are my personal experiences during my stay here, things might be different when you get here. Overall good value for the money. Have a good stay!