We stayed four days at Howy's and it was great. The location is just perfect, in the best area of berlin when you are visiting the city, very close to everything in a neighborhood full nice small shops, cozy cafes and nice restaurants (don't miss the Clärchen Balhaus). You can easily walk to the main attractions (or even better, rent a bike in the shop located next to the flat: fahradstation).
The apartment is minimalistic (little furniture) as you can see in the pictures but charming. It is very bright (take your mask if you like darkness to sleep) and quiet at the same time because it is overlooking a lovely courtyard.
Howy was quickly helpful when we needed some extra stuff, and he was flexible for a late check out, so we just can recommend the place.