Spend your holiday here! It is a nice and cozy place, small but offers everything you need. It is quite easy and quick to find when you step off the bus at Taksim square (your main hub for trains and all). The balcony offers a great view over Istanbul and while you are right in the center of it all (that includes noisy nightlife) the apartment itself is located in a quiter sidestreet and especially with the windows closed at night even a light sleeper will have no problems catching some Zs. Ugur is really nice and will help you with everything you need. He even put up touristy information down in the hallway with all the info on how to get there etc. so even if you decide on a spontaneous trip with not much of a plan or some device to use the free W-Lan you will have no problem getting around and experiencing all that Istanbul has to offer. The Istanbul card comes in handy too, cheaper train tickets! There is no AC but a big fan and a watercooler. (Don`t drink the tapwater.) The little shop facing the house is open until around 1am and will not even attempt to charge you tourist prices.
Have faith in the rather narrow spiral staircase, it is not for people on crutches though I reckon.
The bed is actually big enough even for tall people (so is the bedding) so us asking for an extra blanket (which was free, we also did not have to pay a late fee even though we came past midnight) was unnecessary.
We can only recommend this place! :)