I'm not sure how much I can add to the already glowing reviews of Missy's place - you know the view is to die for, there are stairs (but Istanbul is a steep, steep city with erratic 'sidewalk' areas, so people who have trouble walking are hopefully not flocking here in droves as it is!), and it's a small, adorable studio (I was SO comfortable as one person, but I couldn't imagine it for any stretch of time with even just my boyfriend added in.) Missy and her sister could not have been nicer or more helpful - at check in, and touching base with me periodically throughout my stay.
Some on-the-ground observations that may help those reviewing for a possible stay:
I work remotely and NEED internet for hours per day; even though I brought a separate satellite modem, I didn't even turn it on while I was there --- I had no trouble with strong and consistent signal from the unit's wifi the entire time (aside from one overall power outage, but that [and the one short water outage] is part of life in Istanbul: such things can happen and should not be surprising). Signal will NOT extend onto the deck, however.
There is a hairdryer in the apartment, and it is quiet and effective.
There is a washer/dryer combo in the apartment: you may know these don't dry to the extent American are used to clothes dryers drying, but thinner items may emerge ready to go, and heavy or cotton items will just need a spell on the provided drying rack.
The pictured gazebo-like tent was not in place while I was there, possibly because spring is a windy season in Istanbul and it's not safe to have it in place! But be aware, you are overlooked not just by neighbors, but by a whole restaurant! So I can see, if in summer the gazebo returns, it'd be nice to also have that privacy (in addition to the shade and rain shelter.)
Bring eyeblinds if you are sensitive to the light: there are perforated miniblinds that shade the light, but nothing to darken the sun that will stream in. I also wasn't *quite* sure they shielded my modesty from the construction crew working on the across-street which was slightly uncomfortable: the bathroom is beautifully redone but a bit tight for changing clothes. I ended up using the cupboard doors as a screen for getting the essentials on.
The radiators worked almost instantly to heat the place up during evening chills. There is a minisplit AC that I had no occasion to try but should work fine to cool this small space.
Your location for transport connections is just amazing, with the T1 tram Tophane stop a few minutes steep walk down the hill, and the M2 metro line a few minutes' steep walk up the hill (Şişhane stop). Not to mention the adorable İstiklal tourist trolley stops outside the Şişhane stop as well, though the volume of people packed inside varies throughout the day, often being too crowded to squeeze onto pleasantly.
The Kılıç Ali Paşa Hamam is just behind the Tophane tram stop; do yourself a favor and book the traditional hammam ritual in this gorgeous historic building. (There is a gift shop there too with actually fairly reasonable prices!) There is an A101 grocery near this tram stop as well, on the AirBnB's side of the small park; also there's a Sok grocery store on the other side of İstiklal (go up the hill from Missy's, cross the street, then down a few blocks). There is a tiny convenience mart just downstairs at Missy's, fine for restocking your bottled water or getting juice, but the lanky gentleman who runs it is often not there with no indication of when he will return, so it's luck of the draw whether he's open when you stop by or not.