My husband and I stayed in Paul's place for a week over Christmas.
The location is amazing - just steps from the Pompidou and in a lively neighborhood with lots of restaurants. Other reviewers complained of noise, but we didn't have any issues. It was also incredibly easy to get to and from the airport and a quick walk to the metro to explore the city.
The apartment is definitely small, but had everything we needed. The futon bed was exceptionally comfortable - we slept wonderfully all week. The kitchen, while tiny, had everything we needed to cook up an entire Christmas dinner!
The only possible downside I could think of is the bath/shower. The showerhead does not hook up to the wall so we had to take our showers sitting in the bath. Also, the hot water doesn't last very long so we had to take quick showers at different times of day. But all in all, that was a small inconvenience in an otherwise ideal Airbnb.