We enjoyed out stay in Erdal's Studio. It looks exactly like the photos, clean and cozy, but on the small side. Erdal and her niece were very helpful and always very quick at responding to any questions we had.
The location is good, it does involve a fair amount of waking to reach most destinations, approx 10-15minute walk to nearest tram. However Istiklal Ave is very close and convenient to get to locations if you enjoy walking around. The area is very safe and lively although the roads and sidewalks can be quite uneven.
Overall we would suggest staying with Erdal and feel as though this is a good place for young travelers to explore the less touristy side of Istanbul.