I spent 34 days in Mario's bright, spacious apartment, and it was so roomy, I didn't quite know what to do with myself!
The furniture in the living and dining areas is tasteful and well-chosen — I'd consider reupholstering the white leather sofa in fabric, though, as the leather may flake. (Just a thought.) The kitchen was a joy to cook in, which was great because I love to cook. I may have left the spice and condiment pantry a little better stocked than it was when I arrived, haha. There are two full bathrooms, which is always a good thing if you're more than one guest and you're not a couple.
My favorite thing about the flat is its proximity to public transportation. The U5 is almost practically next door, and the tram is just a little past that. There are great cafes for brunch all over the area, and a well-stocked REWE two tram stops away if you're a little too lazy for a short walk. It was the most convenient home base in Berlin. (Also, the building has an elevator, which was a godsend because even though the flat's not on a higher floor — I would always take the stairs, in fact — I had two suitcases and a carry-on with me that would have been a pain to take up and down, haha.)
I'll echo some other comments in that the apartment is situated on a busier road, so you will hear a little traffic every now and then if you're sleeping in the living area, but it was never a problem for me personally. There's currently some construction going on, but I knew to expect it because Mario disclosed that information even before I booked, which I appreciated. Communication with Mario (and Carla and Felicitas, in Berlin) was a breeze, despite multiple time zones, and I really appreciated that as well.
Thank you for a lovely month in my favorite city on earth! I had a wonderful time in your home. Looking forward to visiting again.