I have visited Paris 6 times,and this is the only hotel I have stayed in twice,so I don't understand the terrible reviews. I have stayed in much more expensive places,but this Hotel has everything you need for an excellent price.Yes it is an old building,that is the beauty of Paris,and small rooms are typical of 99% of Parisian hotels. Our room was immaculate,the bedding was fresh and clean and the bed was very comfortable. The bathroom was compact but had everything we needed, and it was perfectly clean.The shower is excellent too.
As for the area,yes it is very busy due to the line 4 metro, bus and tram stops so conveniently outside,but that is why I love this place. 20 minutes on the metro and you can be visiting Notre Dame or sitting in Le Jardin de Luxembourgh. It is a perfect base to explore the whole of Paris. It may feel a little unsafe if you are a woman walking alone,but I did it several times and had no problem. It is also only a ten minute walk to the beautiful Sacre Coeur basillica, though it will keep you fit walking up there!
The staff were polite and helpful,and I would not hesitate to stay here again. Our only downside was the noise from building work which started very early in the mornings,but we do understand the building and the area are probably all getting prepared for the Olympics.
Bottom line,give this place a chance. If you want the Ritz,book the Ritz, but I prefer to experience Paris the way the locals do.