The (actually safe) neighbourhood looks really rough and run-don, but the house is nice from the inside and the owners seem to be really nice people judging by mail contact. But it's a little hard to find and took some walking from Taksim.
The room is a cellar room which makes it dark, musty and loud because the window opens towards the street on ground level so you'll hear people screaming, an occasional car and a lot of children playing until late at night. But the price for that room is really unbeatable so if you aren't sensitive, stay there. It takes a bit of a walk to get to the old town of Istanbul or the next public transport, but it's doable if you're good an foot. In general in that neighbourhood there's a lot of interesting cafes and bars.
I originally intended to stay for a couple of days, but I moved out the first night because of a major problem: A third of the brick walls were covered in white and black mold. The owner explained to me that the walls used to be wet, but got worked on and the problem is no more. But with all due respect: Then get a bloody brush and clean your walls from that mould as the spores will remain active and harmfull even if the walls are dry now. So they gave me a refund which was very friendly. If they solve that problem and have the walls cleaned, if you're not scared by a rough neighbourhood and some noise, then the price is really superb. And the other rooms in that building should be better in that respect, so you might want to stay there.