Great location in les Batignolles, one of the most fun areas of Paris -- surrounded by many great restaurarants, tapas bars, and cafes. Close to several metro lines and the RER.
The apartment itself is quite nice -- dining room and salon, small kitchen, and a small bedroom with ensuite sink and bath, but no toilet -- that's out in the hallway by the kitchen, surprisingly far from the bed.
It's up 4 flights of stairs, which reduces street noise, but is a bit of a hike with heavy luggage or if you're going in and out a lot.
One concern is the railway tracks -- there are eleven sets of tracks, all of the lines going into te Gare St-Lazare, directly below the apartment. There are trains roughly every minute during the day, and one every few minutes during the night. We didn't mind too much, but one of us likes to wear earplugs to sleep. Mght be a problem for a light sleeper.
Another thing to know is that the owner's stuff is everywhere -- clothes in the closets, bins of shoes in the bedroom, hundreds of nicknacks everywhere, dozes of photos on the walls, etc. -- you're staying in someone's very well lived in flat. It's the opposite of an anonymous commercial apartment. We didn't mind, but some people might.
Overall: recommended, if you don't mind the two caveats above.