I think besiktas is the best neighborhood you can stay at when u visit istanbul. All transportation means are close by and you can go anywhere from there (all attractions are max 20min away). The area is great it has everything u need (coffeeshop, restaurant, bars...etc) all within walking distance.
About the loft, it is very clean and kerem provides towels, slippers, coffee and other refreshments too. It is cozy and has most of the things u need.
Cons: 1.the stairs are narrow and a bit steep. My husband was with me so he carried all luggages. If i was bymyself there is no way i would do it (i even felt bad for him carrying 4 big suitcases)
2. The sink in the bathroom is soooo small but It is not a big deal since you can use the one in the kitchen.