I had a great time staying at Andrew and Olivia's place! I got into the city earlier than check-in, but ended up being able to check-in early thanks to the lovely woman who helps with the cleaning. The room is comfortable for one person, might be a bit snug for two but would be fine if you're mainly spending time seeing the city. The bed was comfortable and there's a small fold-out table attached to the wall that can be used for work or for eating. The kitchen is well stocked and they have all the components for a light breakfast: toast, eggs, butter, jam, tea as well a number of spices and cooking oils.
The apartment building is located just inside an alleyway off of a major street which can look a bit foreboding at night. As a solo female traveler, however, I never had any issues, although I did take a taxi home some of the nights I was out a bit later (probably wasn't necessary). The downtown area of O'Connell street is maybe a 10-15 minute walk, Temple Bar would maybe be an additional 10 minutes. There are plenty of nearby bus stops, which makes getting around easy, and Andrew and Olivia have compiled recommendations for things to do and places to eat that I found helpful. There are also a number of restaurants nearby and a small grocery store maybe a block away.
The only downsides were that the latch on the front door can be pretty loud (there's nothing you can really do about the noise when you're leaving the apartment), so with several other guests staying in the apartment, that noise could be disturbing to some. Also, because the apartment is shared with at least two other Airbnb rentals, there's some unpredictability in terms of noise. This room is on one end, so only shares one wall with another of the rented rooms, but the walls are fairly thin, so that's something to keep in mind if you're a light sleeper.