Arno's place is wonderfully located in central Paris. Most of the things a visitor would want to do are in walking distance or a quick Metro ride away via the Strasbourg - St. Denis station. You're also very close to the wonderful shops and restaurants on Rue Montorgueil as well as the giant Forum des Halles shopping center. Also don't miss the nearby Rue du Nil. It's tucked a little out of the way, but we ended up visiting the delicious Boulangerie Terroirs d' Avenir for pastries and Frenchie to Go for coffee most every morning. The apartment itself is comfortable, well appointed, and tastefully decorated.
A few things to note:
* It is a courtyard apartment surrounded on all sides by 5 floors of flats, so be forewarned that there's not much breeze. This will likely be fine in most of the time, but it was very warm during the heat wave that happened while we were there. The windows on the first floor don't have security latches where you can leave them open but keep them from opening wide enough for someone to enter, so we weren't comfortable leaving them open at night, and this definitely made us warmer.
* The shower and sink are on the second floor, with the toilet and a small handwashing sink on the first floor. This might be an issue if you have very little ones, as the stairs are steep and narrow with no handrail. Our 4yo was fine, but it made us nervous the whole time.
* There is a subtle 1" rise in the concrete floor between the living area and the 1st floor bedroom/wc/stairs area that's not marked in any way. I point it out only because it's very easy to miss and easy to forget. My wife stubbed her big toe and broke it on this lip on the 3rd day we were there.
All things considered, though, this apartment is a good value to be so close to great amenities and easy transit! It had most everything we needed, and it was a good fit for 2 adults and 2 kids. It's not perfect, but we'd definitely consider staying here again.