These guys are fantastic. Great security, very clean, friendly staff, and beautiful grounds. If you're looking to stay in Kadikoy, this should be your first stop. The vibe is fairly quiet, so if you're looking for more of a party I suggest checking out their sister hostel, Hush Hostel Moda, which is located just a few blocks away.
The grounds are beautiful and we met some really cool people here. But the staff aren't friendly at all. The owner is accommodating if you have questions, but he won't seem happy to be talking to you at all. We actually found him to be pretty rude. Also, our room had a private bathroom which is nice, but it smelt so strongly of mold/mildew in there that we had to keep the door closed and use the communal bathroom down the hall. Still, the garden/pool area and grounds in general are really nice.
The staff is awesome. They're super friendly and they really want you to have a good time. The rooms and facilities are nothing fancy, but clean and comfortable. The terrace bar on the top floor is a great place to hang and meet people and the view is breathtaking. We made some wonderful friends up there. Breakfast (included) is also really good. Again, nothing fancy, mostly raw fruits and veggies and some hard boiled eggs, but it's all fresh, and very tasty after a long night out.