Great location and staff are excellent
My wife and I have just returned to Gibraltar from a 5 day break in New York and stayed at the Cassa Hotel.
The hotel is in a great location and is modern with excellent staff. Our room was clean and well furnished (bed was a bit small) and the bathroom was spotless with a huge walk-in shower. We were on the 17th floor at the rear of the building and heard no street/traffic noise at all. 
The only drawback we found was that there is no tea or coffee making facilities in the room, however there are plenty cafe's and deli's in and around this block. 
There is no bar in the hotel but work is going on to open a brasserie early next year I believe. Again though, there is a huge choice of bars and restaurants in close proximity, we used one just down 45th called the Perfect Pint for a few drinks most nights and it was excellent with a great atmosphere.
I'd definitely recommend this hotel and would have no hesitation booking it again as we found all the staff very helpful and friendly. Everyone of them we came across took the time to talk to us when we were coming and going and hotels over here could learn a thing ot two about customer service from the Cassa. I wouldn't normally mention specific staff, but Patrick who checked us in was particularly helpful and Gabriel was always cheerful and friendly and nothing seemed too much trouble for these guys.