I loved Arnaud's apartment in Le Marais...the location is perfect, there are dozens of markets, brasseries, and really cool little shops within walking distance, and the Metro line #8 is half a block away.
Arnaud was a lovely host, he met us at the apartment and helped us upstairs with my heavy bags, he provided some interesting info about the area and a few websites with Paris info, as well. He is very charming and accomodating. His apartment is adorable and comfortable and had everything we needed for our stay, including an umbrella for when it rained, a computer and also some dvds! The decor is cute and contemporary, the bed is comfortable and the shower was decent pressure too.
One thing you may want to know: We definitely didn't mind, because we are very active anyway, but there isn't a lift and it's on the 4th floor. Though I have to say, many Parisien buildings don't have a lift, as they are older, and Arnaud's place was certainly worth walking up all the stairs.
I will definitely try to stay here again and would recommend it to any of my friends. We had such a great stay here.