The location is unbeatable: you're right in the center of the action, close to transit (train to CDG in 35 mins), and walkable to anywhere in central Paris. The apartment was also clean, and there were plenty of linens and towels for the five of us (4 adults, 1 child).
On the down side, the description reads "2 bedrooms", and it's really one bedroom and one living room with a bed and two sofas. We booked at the last minute, and I should have read the details more closely, but I think this is important to know. The host lives in the apartment, so it is filled to the rafters with his things; as other guests have noted, there are no empty drawers or closets to store clothes.
The area around the apartment is very safe, and there's no traffic because it's a pedestrian zone, but it's a busy part of the city with a lot of nightlife, so there is a good amount of noise late into the night (esp. on weekends). On the plus side, you can monitor the queue at the Centre Pompidou without leaving the apartment, which is nice.
As I mentioned, we booked this apartment at the last minute (9 hours before arrival), and Frederick was a very gracious host for receiving us with such little warning. He met us at the apartment in the evening, showed us how everything worked, and was communicative during our stay.