We stayed in a top floor apartment/room, with windows to the "plaza" and shopping center. It gets very warm inside even with just a bit of sunshine and around 18-20°C that we had during our stay. I would not stay here in the middle of the summer, although it can be partly solved by using the windowshades, that are very good (electric shades that roll down on the outside of the window), and then opening the windows in the evening.
Earplugs are pretty much mandatory. It seems like the street outside is a main pathway for ambulances throughout the day and night. There are VERY loud sirens passing by every 5-10 minutes on busy evenings and at least every 30 minutes on a calm evening. It was probably my top dislike about this place. With earplugs it was ok. There's also the occasional drunk or madman screaming outside at night. Your normal big-city noises I guess.
The convenience of having less than 100 m to the U-bahn is a great thing that almost makes up for the noise. The apartment itself is very neat and newly renovated, and has all you really need. The dishwasher is one of the main reasons we chose this one but in the end we didn't even use it.
It's nice to be able to leave luggage on site before or after check in/out, in a room that is either locked or has a person in it, it felt safe. Although the staff-on-site times seem to vary from day to day so you might want to check with them beforehand to make sure it works for you.
Cleanliness seems OK but we noticed our 1.5-year old son had very dirty feet after running around in the room for a bit, in the first hour after arriving. So apparently the floor was not very well cleaned. Other surfaces seemed clean though. The bathroom had a bit of a funky smell to it, but I've felt worse.