We very much enjoyed our stay at Segire's converted factory in Canal St Martin. It was such a unique and fun experience to stay in this converted factory in a courtyard, steps from the canal. The neighborhood is a bit edgy but gentrifying, with lots of good dining options. Though it is not in the center, Uber service is great to anywhere you'd like to go. The place is quite large, private and quiet ... like your own little cottage. It is very clean and well equipped.
Things to be aware of ... except in the kitchen, all of the light comes from skylights and interior windows. While there are fans in every room that work well, this can be a bit claustrophobic. The only way to get air or a breeze in was to prop open the doors to outside, which are semi-public. Even in the heat of July we were ok with this, but it is something to note.
Also, the bathrooms are on the first floor and the bedrooms are all on the second floor. I don't think this would work well for anyone elderly; the steps down are very irregular and can be tricky in the dark. I would also note that the bedrooms not provide any real privacy... glass panels allow in light but they also undermine privacy (no curtains). Lastly, the bedrooms do not have closets.
All that said, it is such an interesting and pretty property, in such a fun area, with so much space, that I would rent it again and reccommend to anyone patient with its quirks!