Rather unspectacular
This particular W seems to be coasting on the reputation of the chain. If you can get a great deal on a room (check the AAA rates), then take it; but I wouldn't pay more than $250/night.
What's GREAT about it: the location can't be beat for midtown. 50th & Lex, easy walking distance to Central Park, shopping and several subway lines. The Bliss bath products are a plus. The gym is supposedly very good but we didn't use it.
What's GOOD: the concierge was helpful and friendly.
What's BAD: the rooms are microscopic. Knowing that NY rooms run small, we booked one of their supposedly slightly larger rooms - in the "spectacular" category (there are actually two entire categories that are smaller - "cozy" and "wonderful"). Our room was extremely tiny (even for New York) and also very dark (little natural light and dim in-room lighting). The air conditioning was very loud. The staff at the front desk could be friendlier.
Overall: there are better deals in New York. We'll try the Affinia chain again in midtown for our next trip.