Staying at Daniel's apartment was a very good experience. It is located at 6 to 7 minutes walk to almost the middle of Istiklal Street and there are many many restaurants and shops around it even before you reach Istiklal Street.
The place itself is very comfortable and has all the facilities you need. it is spacious and very sensibly organized.
The apartment is on the second floor plus mezanine and therefore carrying heavy luggage could be a bit of a challenge for some people.
All in all, it was a good stay and we would recommend it to our friends planning to come to Istanbul and staying in the Istiklal area.