This apartment has 3-1/2 levels. The first has a small kitchen/dining area with 2 separate toilet rooms (with sink). Next level is a loft area adjacent to the kitchen - up here is sofa bed, small desk and TV. It's a good gathering area if you're not using it as a bedroom.
The next level is the first bedroom (Queen) with a shower inside (with a sink). The top level is another bedroom (Queen) with a shower inside (with a sink). The bedrooms are small but sufficient space for luggage and clothing.
The spiral staircase leading up to the bedrooms is tight and steep. Not an issue for us, however, if you can not climb steep stairs with 30-40 pounds of luggage - this would be a difficult feat.
We had 3 people in the apartment, each with their own bed. Plenty for space for us. I would say it can accommodate 5 people easily (assuming 2 couples and 1 single person).
The apartment is clean. You will have to use the electronic key fob twice (front entry and internal entry), then a coded keypad for the front door.
Brasserie Dubillot is directly across and a great place to eat. Also, there is a Monoprix market a block away for snacks, wine, etc. Overall this location is very convenient with easy access to Metro, markets and restaurants.
If you're in Paris for 4-days or more, purchase a weekly metro pass for ~$22; includes RER to/from Airport and Versailles.
Prior reviews mention ladies of the nights nearby. Yes, they are out there, but not an issue unless you are bringing children and don't want them to see such sights. And it's only this particular block - other than that, you can look away and be on your merry way.
As for safety, we felt complete safe here in this apartment and location.
Overall, it's a good location in the 2nd arr. Easily navigable via metro and easily walkable. We averaged about 8-10 miles walking per day and we used the metro a few times each day.