The positives: stylish interior design of the room and plenty of space; really convenient location for exploring Istanbul and had numerous local food/drink options; great communications from the host team; and good value.
The negatives: the combi boiler wasn't great so the shower hot water only lasted a couple of minutes; and the local area was really noisy at night. On the latter point, we live in a city and have stayed in numerous cities, so we're used to a bit of noise. However this was notably worse with music playing nearby until the early hours. Our sleep was disrupted every single night, particularly on Friday and Saturday. I'm really surprised this hasn't been noted in other reviews.