The good: Location is A+. The Louvre taxi stand is directly across the street, and the metro station for 1, 7 and 14 are within a block or two. There is a grocery store in the same building next door, and many bus routes are within a block or two. The elevator does go to the sixth floor, though the apartment is on the seventh floor (US version of floors). The beds were very comfortable. The building was quiet and felt very safe. We had to walk to go pick up an infant bed from the Sweet Inn office, and the staff there were extremely friendly. Wifi worked well. Top 40% of the Eiffel Tower can be seen from an upstairs window, which was really nice, especially when it sparkled at night.
The bad: Sweet Inn staff doesn't have much of an idea about the apartments. I asked right after booking if the elevator went to the floor that the apartment was on, because we had an elderly person who couldn't walk well, and they told me yes. When I checked again a week before coming, they still said yes until I pushed back saying there were new reviews that said it wasn't on the same floor. Very frustrating.
There were also numerous maintenance issues. The downstairs bathroom is pretty much unusable because every time it is flushed, sewage from the toilet seeps into the vinyl flooring, creating a mushy flooring where toilet water comes up on your feet. It also leaks a little sewage water into the living room. It's shocking that Sweet Inn hasn't fixed this. There were numerous light bulbs burnt out, especially in 2nd floor bathroom.
This is NOT a three bedroom unit. The third bed is in an open area that must be walked through to get to the second bedroom. I highly don't recommend banking on a couple staying in the third bed.
There is a microwave oven, but for somebody not from Europe, it's very difficult to operate. We even googled the instruction manual from IKEA and still had trouble figuring it out.
There are only one set of keys, and that set of keys is needed not just for the apartment door, but to access the rest of the building from the street. So, if you have people planning on splitting up for the day, it's extremely inconvenient to have to coordinate meeting up to trade keys.
Don't forget to fill out the form online they send you after booking. We had to wait 50 minutes to check in, but that was our fault since we arrived early and didn't schedule the check-in ahead of time.
Overall, I would not recommend staying here, unless you see follow-up reviews that state that some of these things are improved. If you feel like you're getting a good deal though, maybe consider it, because the location is really good.