Not bad, but not good for everyone.
I stayed at the Ace for 2 weeks. The rooms were small and dimly lit but clean. The staff were always smiling and friendly. The housekeeping always wrote us little thank you notes for our tips. 
I'd recommend this place to younger travelers and tourists on short visits to NYC. Its probably not the best hotel if traveling with children (the bar downstairs attracts quite a crowd most nights). I also wouldn't recommend it for business travel for longer periods of time if peace and quiet is something you crave after work.
The first 11 days we were in a pokey little room on the 2nd floor with an internal facing window and a series of minor issues with our room that culminated in a late night room change to the 8th floor and an anger-fueled hotel review. 
In summary, my main complaints (with the 2nd floor) were:
1. Noisy: Thin walls and doors. First room was too close to the ice machine and housekeeping closet, waking us up late at night and early in the morning.
2. Dark: Black carpets, very little natural lighting. Depressing for longer stays if using the hotel for anything more than sleeping.
2. Trendiness over practicality: The room furnishings were impractical for long term use - we couldn't fit our legs under the table and we'd cut or jam our fingers opening the fridge.
After the move to the 8th floor we got natural light, the room was quiet, the layout both comfortable and practical. All the points made above were essentially resolved. Management too took an incredible interest in our dissatisfaction up to this point, calling and emailing to see if there was anything else they could do to make our experience more enjoyable. 
At the half-way point, I would have rated this hotel poorly on the grounds that the room was depressing, uncomfortable and inconvenient. By the end of our stay however, based on our new room on the 8th floor and the amazingly responsive, friendly, apologetic and understanding attitude we got from staff after the move, I can't honestly rate this place as "poor". The staff here actually *do* make all the difference.