Catherine's place was perfect for a couple's 5-day trip to Paris. The double bed is a totally acceptable size for two people and very comfortable. The kitchen is sufficiently equipped for cooking simple meals. The TV is a smart TV and there is lots of storage space available.
It's as small as it says it is in the description - the toilet is incredibly cramped, you can barely stand up with the door closed, when the sofa bed is open you can only walk in single file etc. The shower is full size though. We didn't mind the size but just note this if you have mobility difficulties. The decor is very neat and nicely done so it's still a pleasant room.
The breakfast was some fresh bread given on day 1 which unfortunately was stale by day 3, jam, butter, hot chocolate, coffee, tea.
The location is perfect - we walked home from the fifth, sixth, second and other surrounding arrondissements and the walk goes through lovely streets with cafes, bistros and other action. It seems quite a safe area, bars and restaurants on your doorstep, there was live music nearby one night. A great, lively but not wild, atmosphere.
I recommend Catherine's place as long as you don't mind cramped space.