Not Ready Now -- and Perhaps Not Ever
Just as the old Helmsley re-opened as a Westin, after renovation and re-branding, I have just stayed four nights, and will not do so again any time soon. The physical work is not yet completed, but the many short-comings are those of attitude and scope of service, which are not likely to be solved.
For starters, the "Grand Central" designation is a stretch, as is the haul with luggage the three long cross-town blocks from the address, between Second and Third Avenues.
Staff help was decent, including a very helpful concierge who arranged for some document printing.
But the overall attitude is cheap and cheesy -- including plastic cups in the bathroom, a pile of USA Today by the elevators instead of Times or Wall Street at the door, no service guide in the room, a key card dysfunction that forced me back down to the desk for a re-load, and one day when my room was not serviced at all.
Worse, from the perspective of a business traveler, is the annoying approach that everything is charged extra: $21 for a "continental breakfast," when there are numerous Starbucks just around each corner; a "business center" that charges by the hour for computer access; $ 14.95 per day for WiFi; and a truly obnoxious mini-bar that would bill electronically if anything was even moved. 
In short, human touch has been sacrificed for a nickel-and-dime attitude.
The old joke about New York is that it would be a great city, "if they ever finish it." As for the Westin Grand Central, even if it gets finished, it will be far less than great.