We (a young couple and a small baby) spent one week in the apartment in October 2015.
We were looking for a convenient place in Beyoglu and from a location point of view, this was excellent. The apartment is less than five minutes from Galata tower and about the same distance to Istikal street. We also walked to Topkapi palace with a baby stroller (30 minutes walk). It is also close to the subway which we didn't use so can't comment. Also close to the apartment are numerous great restaurants and everything Beyoglu as an area has to offer so all in all everything is close by and convenient.
Izel (our host) was kind enough to provide a tour of the area and walked with us so spent more than 30 minutes showing us around the neighborhood and how to easily navigate. Izel also made several restaurant recommendations which were all great. We were provided with a map, a local phone, transportation pass and Izel also took the time to recommend some places we could visit which we thought were interesting on the Asian side.
The apartment is clean and well kept and has lots of space. It could easily accommodate more people. It has two spacious bed rooms, very nice dining area with a living room as well as a kitchen with everything you need for cooking.
Because our trip was in October, we wanted an apartment with heating as we have a small baby and it can get chilly in Istanbul in October and while we were lucky with the weather we did turn on the heating one night and it worked as expected.
All in all, we were very happy with the apartment as well as the excellent communication and reception by Izel. I can recommend this apartment and the host without any hesitation and we would happily stay here again.