We love the 25Hours hotels, particularly in Florence. The Paris Hotel has the same inventive approach to decor and finishings. The location is great if you're connecting through Gare du Nord, and it's convenient to all attractions in north Paris.
The in-house restaurant, Neni, was a real treat. It's casual, the food was excellent and we had a view of the station.
Our room was well appointed, with a serviceable desk, a good safe (held my laptop with a mm to spare), a good shower and a balcony (which is often hard to find in Paris).
Our only issue was street noise. That can be an issue in any large city, but it was more noticeable for us this trip. We had a room facing Bd de Denain, and the sound of night life in Paris (shouting, traffic, the occasional dispute) was intrusive. Obviously that's not on 25Hours and there is nothing they can do about the noise, but when we return we'll ask if there are rooms that don't face Bd de Denain or Pl Napoleon III.