The place is ok to sleep only, but not if you are planning to get home and have peace after a long walking day as you usually do in Paris. My room was messy, this could have been because of my roommates were a bit unorganized.
Since you have to lock the door consciously and there are many people there it might happen that you come back and the front door is unlocked and anyone can get in.
The place around the property doesn't seem too nice but I think in Europe shouldn't happen anything to scary.
On the other hand it is central enough to get to interesting places quite quick and by foot and the metro station is directly outside of the building.