My sister and I stayed at Angie and Chris' Josephine loft in the Opera district for a week in August. The apartment was as-described, and very clean inside. The bed was large and comfortable and the shower was very modern.
Unfortunately we weren't able to meet Angie and Chris, however their friend Enoc was lovely and helped us check in before showing us how to get to the nearest grocer (he was also very patient with my stilted French!).
We loved the location because it was far enough from the tourist hotspots to be relaxing, but close enough to keep us busy. The apartment is near three major metro lines and an easy commute to and from the CDG airport. It's also walking distance to the Folies Bergere, Galeties Lafayette, and the Palais Garnier (all well worth seeing).
Angie and Chris have some great suggestions in their blog and in the apartment for places to eat and things to do - you should definitely give them a try! We especially enjoyed Super Nature,
We would each happily stay here again when we are next in Paris!