I stayed at the "Happy | Cute Studio Concept" for 11 days and had a wonderful experience.
When you read the listing description, you can see that these guys put a lot of time and effort into it, which I liked a lot while making my reservation, so I didn't have to ask a lot of questions.
The ad and pictures are current and cover the entire listing, so there will be no surprises.
The check-in procedure was quite smooth, and the personnel was extremely kind upon arrival. They even offered to have someone from their team accompany you to your reserved spot and show you the apartment's features. They also have a welcome desk that is open 24 hours a day.
The location was incredibly convenient for me, and everything I needed was within walking distance, which eliminated the need for a taxi, which was a great bonus for me.
Expect some street noise, as with any other apartment on a busy street, but it wasn't a significant deal for me.
Apart from that, everything was fantastic during my stay, and I would certainly stay there again or check out their other listings when in Istanbul.
Güner and crew, thank you.