Arriving at night, we had no problems, nor I found the area at any nights scary or unsafe. On weekends the Saint-Denis underground station area was lively, with lots of people around, young and old.
The room was small, but it had all you need in it. By far the cleanest and nicest room I've stayed at in Paris. The bed was comfortable, and we slept great. There was a coffee maker with capsules also provided in the room, and tea bags. Lots of hangers, a safe box that would fit a laptop, a whole body mirror, good shower with warm water, makeup mirror and a hairdryer. What I liked the most about the room was the lightning of the bathroom. Wifi worked on all devices at all times.
Very clean room, and it was cleaned twice during our stay - even the sheets were changed.