Just a quick update for those tracking - did receive a Diamond upgrade when we arrived, but only after asking about the possibility (which seems to be a theme in my short stint as a Diamond thus far). We had to go down from a room on 52nd floor facing south to one on the 40th floor facing north, but the views are very much worth it.
I can't speak to how the property compares to other Conrads, but I've found the service to be quite good, and the room size/luxury is pretty stellar as New York goes. It's been far better than our last stay at the Waldorf, though that's maybe not apples to apples.
Only knock is the breakfast setup - as others have noted, the fact that even Diamonds don't get comped the full breakfast is a little ticky-tack. Plus, there is literally no universe in which this buffet is worth 38 bucks. I'd take the spread at the Hilton Midtown, which at least has a good variety of items. There is no bacon and eggs worth $38.