This a charming attic apartment with good light and a fairly convenient location. We stayed a week. Two of us never felt particularly cramped, although the ceilings are low and spaces tight. I'm 188cm (~6'2") tall and managed not to bump my head once, but was right at the limit for convenient use of some of the spaces (kitchen and shower). Any more than 2-3 guests would start getting very close unless they were small people or good friends.
Street parking seemed easy to find; the offered parking on premises seems to involve careful coordination and car shuffling. S-bahn (3&7) and U-bahn (2) stations are about 15' away by casual walk.
The kitchen is limited; the proprietor offered use of the oven on her floor, otherwise you're limited to toaster oven, microwave, and 2-burner range. We made do when we cooked in; the kitchen is right-sized for casual cooking for 2-4, so it works.
The proprietor keeps a clean and neat house and has a fairly extensive list of house rules. If you're not a tidy person, it might be best to find another location.