I like to do reviews in list form, with pros and cons clearly outlined.
Pros:
The apartment is super cute, and matches the listing - which as some of you know isn't always the case. The photos do a very good job of giving you an idea of what the apartment looks like and feels like.
Don't be fooled buy the outside of the building - it looks like you're in a bad part of town in a US city - but you're not. The location is actually really GREAT - very close to the Toledo and Università stops on the metro, which makes it very easy to get to anywhere you want to go. There is A LOT of night life around this area, because the apartment is near the University, so there are a lot - A LOT - of young (18/19) kids out at night drinking and smoking and partying and it can get loud. We heard literally NONE of it from the apartment. The soundproofing is AMAZING. There are a lot of bars and restaurants in the area - but I think our favorite was Tandem, which it literally out the door and up the block (get the gnocchi in the ragu, my husband got it and while my ragu was delicious they added some cheese to his that made it THE BEST). A short walk away is a great breakfast joint called Ceraldi Caffe. The coffee and the pastries are delicious - and if you're in the mood for an "English Breakfast" they serve it all day long (we didn't get it so I can't vouch for it's quality). There is a GREAT pedestrian only (meaning pedestrians AND scooters - careful they drive very aggressively) street - Via Benedetto Croce - just up at the next piazza.
Mariella has an extensive guidebook of things to see/do/visit/eat in the area around the apartment and in the greater Napoli area.
The A/C works well.
Marco, Mariella's friend who helps her with the apartment, is super friendly and helpful and easy to communicate with. So is Mariella.
Cons:
Check-in is a little different than we are used to: someone meets you at the apartment to let you in and show you the place. This is great in theory, a very welcoming notion, but it made it difficult for us to get into the apartment due to a bunch of stuff out of our control. We ended up having to wait at the apartment door for an hour and a half.
The keys for the apartment are tied into the power for the apartment (the fridge and the wifi plug stay on don't worry). I totally understand they do this so that guests don't use the a/c all day while they aren't there, but it makes it difficult for one partner to pop out somewhere and leave the other one there as there would be no lights or air or anything.
Some of the reviews I read before booking this apartment mentioned a comfortable bed - which is a huge thing when you're travelling. I don't know if the mattress got swapped out or if those people just like stiff mattresses - but my husband and I did not find the bed to our taste. It is a very stiff/firm mattress. But the pillows were great.
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Overall we were really really happy with the apartment. We recommend it to you if you're looking for a great place to stay in Napoli.