The room count remains the same from the Helmsley days (774 rooms), though the good news is that Helmsley rooms always benefitted from being slightly larger than your average New York City hotel room (which is still small compared to other places, but it's all relative). So while size was never an issue, other factors like carpeting, furniture, curtains, etc all definitely were.
All of the rooms have that trademark Westin 'cool, calm, collected' feel with off-white walls, neutral carpeting, dark furniture, a tan armchair, and sleek, dark wooden headboards. Nothing is meant to pop out or make a splash, and that's kind of the point of Westin. The whole look is very clean and uncluttered. It's a significant improvement on the Helmsley's outdated style, which we remember including some gnarly green carpeting and gold-ish yellow curtains. Yeesh.
Of course, one of the hotel's best assets—the view—is something Westin didn't even need to touch. If you end up staying here, be sure to ask for a high-up floor, as you can get an interesting perspective on the midtown skyline, plus up-close views of the Chrysler building, as well as ships drifting up and down the East River.
As for bathrooms, there is some slight wear and tear (obviously, this wasn't a total 100% refurbishment), but still, for the size of the room and the cleanliness, the Westin Grand Central is a huge, huge improvement. We're not sure if you'll necessarily feel "healthier" after staying here, but you'll definitely appreciate the space.
Rates at the new Westin Grand Central start at $269/night, though the hotel is offering 10% off the best available rate plus free in-room breakfast thru March 31, 2013 as a grand opening special.