We stayed a week in New Delhi, several days in Imperial and several in Sheraton.
Sheraton is very efficient, staff really tries to do their best in terms of service quality.
The rooms are spacious and bathrooms are quite stylish! Good testers, including an indian brand of nature cosmetics, which we liked a lot.
Restaurant serves wonderful food, bith local and international cuisine (although pasta bolognese was as far from real one as india is from italy). We were quite cautious with food at first, but had no problems at all (unlike in Imperial)...
The lounge and bar area is great, with live singer every day, huge windows overlooking a garden, decent choice of cocktails and human prices.
The most surprising thing was an email from the hotel after I returned to Zurich, saying that I had left a body lotion in the room and they were willing to ship it to me...How sweet! Even given the fact that I would more than certainly have to pay for shipping - it was still nice of them to get back to me.