The place is great, highly recommend.
Per a few previous reviews, this 4th floor (American reckoning) flat is not a good choice for those unable to negotiate, for whatever reasons, about 86 narrow steps encompassing several sharp turns, particularly with luggage/baggage. This was not a significant issue for us (mid-60s/late 50s couple).
The flat is on a "scenic" little and relatively quiet street (Rue Galande) just south of La Seine, little auto traffic; multiple easily accessible bistros in the immediate hood and in adjacent 5e and 6e. Terrific location (unless you are Le Meurice material), great view from small "terrace" outside bedroom, easy walk to Jardin des Plantes, Pantheon, S. Germain des Pres, etc., reasonably-priced grocery store nearby on Rue Legrange, many boulangeries.
Decorating a matter of taste, we liked. Everything worked including the washer/dryer (in upper bathroom; typical long European cycle, so use during day when you're out & about). Mechanized skylights, modern appliances, excellent lighting, clean, plenty of wall plugs, good internet access. Comfortable queen bed accessed via helical staircase from main flat area, caution required if over 6' 2" (as am I) or risk banging head going up or down. Roomy in comparison to similarly-priced and many more expensive hotel rooms. 1.5 baths (toilet/sink on each level of flat), small but entirely adequate; good shower on upper level, classy fixtures. Variable night noise from street establishments, adequately dampened if necessary by closing windows (place has central AC). Comfortable couch. We didn't use the large flat screen TV so can't comment on function, but it's tastefully camouflaged across from the couch. Also didn't use extra pull-out bed.
Host Michel friendly/responsive prior to our trip; he was out of town during our (August) stay. Both of his friends/flat managers (brothers Lucas and Thierry) easily available via phone or email if necessary.
We loved it.