Nexthouse Pera is a comfortable, reasonably priced boutique hotel in a good location. The bed is comfy, the shower is excellent (very good hot water pressure), and the rooms is well appointed. Service was friendly.
A couple of warnings: The hotel is around the corner from one of the busiest pedestrian streets in Istanbul, so there can be a little noise at times. (Though not enough to be a bother.) The hotel can be hard to find; the signage is small. And they do not accept American Express as payment.