The biggest issue with my stay was that there wasn't a functional thermostat, so my room was extremely warm, approaching sweltering. The room's thermostat had a control to increase or decrease a number, but that number had no relation to the HVAC blowing hot air in or not. The best we could do was deactivate the thermostat and hope the cold air outside siphons heat out of the room. Kudos to the building insulation as it finally got to a decent 22c temperature when we were ready to check out.
The front desk and maintenance staff confirmed that there wasnt any cool air available since it was winter and provided a couple of noisy fans to help. Unfortunately, between the noise of the fans and the heat, I probably only got a couple hours of sleep that night.
Other minor issues include the microphone on the bedside phone not working (making communication with the front desk extra frustrating. Fortunately, there was a 2nd phone in the room) and the display of the alarm clock was damaged (half of the screen didn't display to see what alarm time was being set easily).
For the thermostat related issues alone, I would have to say this was one of the worst hotel stays I've experienced that charges over $200. I dont think I'll come back to the Hilton unless there's nowhere else viable to stay.