I should start that I never write reviews, but when we were searching for an apartment in Paris for 8 nights, I found that the reviews were really the only way to truly get a feel for the space advertised. With that said, I'm writing this review to help you make a more informed decision.
First, Guillaume's apartment is located in the southern part of the Le Marais neighborhood which reminds me of Soho in NY or Soho in London. Small streets with lots of personality, terrific stores, shopping, restaurants and provisions. Within a 2-block radius, we had access to one of the best boulangeries, pateserie, fromaggerie, butch, coffee store, seafood market, grocery store, fruit stand, wine store and pharmacy. The boulangerie down the street is called Hure and quite literally has some of the best baguettes I've ever had. Also, the Le Marais neighborhood has quite a few bars and active late-night brasseries. However, Guillaume's apartment was just far enough away that we didn't have incredible foot-traffic or late night noise. It's still a city and it's not a quiet neighborhood in general, but we found that our block was quite mellow.
Second, there were three of us staying in the apartment, myself, my husband and my 19 year old daughter. The apartment amenities met my expectations. The only bedroom had a big enough bed to fit my 6'1' husband and myself (which was a concern of ours knowing how small European beds can measure) and it was super comfortable. Plenty of pillows, bedding, etc. Our daughter slept on the pull-out bed in the living room and she said it was relatively comfortable. Living room was spacious and accommodated our needs quite nicely. Single bathroom was tiny, in comparison to US standards, but well appointed and clean. There is a washer and dryer in the unit, and we used them frequently. The kitchen is really meant for one person at a time, but had all great amenities: convection oven, small fridge, small dishwasher, convection cook-top, coffeemaker, toaster, and tone of dishes, cookware and utensils.
The apartment is three-flights up, but was never a problem for us. There is a small 2-3 person elevator that we used to get our luggage up and down.
When we were there, the temperature was cool and lovely. But if the temperature was hot, the apartment would have been tough to stay in as there is no air conditioning and only a small table fan available.
But the best part of the apartment was the number of windows; there were 5 huge windows, north-facing, that made the apartment super bright and airy. We would open the windows all day and night and had a cool breeze and lots of light.
If you want a great place in Paris in the Le Marais district, this is a great option!
Enjoy