We really enjoyed the loft apartment - it was perfect for two of us for 4 days. Tucked away in a second courtyard, it was quiet and quaint. Property was clean, everything was functional, so there were no issues of that sort. Jessica was very easy to work with and responsive.
Location is great - convenient to a number of metro stops, also in the thick of the Marais so you can easily get to good restaurants, shopping, etc. We loved Breizh Cafe down the street!
Definitely would recommend - and if we were returning to Paris anytime soon, I would book again. I thought it was good value for the price, especially compared to Paris hotels.
A few things for renters to note (just as FYI):
Definitely enough space for two people, but I'm not sure I'd try for any more than that. I'm not sure where you'd put everything for up to 4 people, and you really only have the sofa and the chairs from the kitchen table for seating on the main floor.
The sleeping area in the loft is a bit tight. It's a Queen-sized bed, but know you need to duck to get in/out and then the inside sleeper (if you have two) has to climb over the other person to get out.
The steps are a bit awkward - as the pictures show it's one step per foot - so navigating can be tricky (especially going down to the bathroom at night and/or if you've had something to drink).
The ceiling is all glass as is the wall... which makes it feel open and airy (the wall opens up too), but not necessarily private (not that I think anyone could really see in, but there are other buildings around with windows).
The bath is a bit tight (from an American perspective), but certainly more than adequate.
The outdoor space is a great bonus (though we had rainy weather and were unable to use it to its full potential).