I stayed at the Westin Tokyo for 1 week in March 2007. I was there for business and this hotel was chosen for me due to the proximity to the office.
I had a very good experience at this hotel. Upon check-in, I was told that I had been given a very special room on the ladies floor. Apparently this is a new idea at the Westin and obviously just for women. All services including porter, room service, maid service, etc. are performed by women and no men are allowed on the floor. I was somewhat skeptical, but when I got to my room, I was very pleasantly surprised. Towards the end of the week, I moved to a "regular" room on a different floor so I can make an accurate comparison. My room on the ladies floor had the same furnishings and layout as a regular room but the extras included Bulgari bath products (wonderful smell!), a yoga mat and instructional DVD in the room, ionic hairdryer, female-specific toiletries like bath oil beads and salts, hair bands and clips, loofah, etc.
Overall, both my rooms were very large by Tokyo standards, the Westin Heavenly bed can't be beat and the service is wonderful, very consistent with Tokyo in general.
On a previous trip to Tokyo, I stayed at the New Otani in Akasaka and the only thing I liked more about that hotel was the location. The Westin Tokyo is in Ebisu which I personally didn't find too lively although there is some shopping and good restaurants and the Metro and JR lines are close by to take you to more "happening" parts of the city.
My only complaint with the hotel is that the on-site restaurants are ridiculously priced. I chose to purchase the Executive package with my room which included 50% off internet charge, happy hour and appetizers and breakfast included on the Executive floor. On my last day I woke up too late to take advantage of my free breakfast and paid the regular price in the cafe downstairs. I think it was more than US$30 for 2 eggs, 2 sausage and 2 small pastries. Tea and juice were of couse extra as well. Its really too pricey for what you get.

Stayed at the Westin Tokyo for 5 nights on business, because most other hotels were booked that period. If mahogany wood, black marble,
golden handles and opulent ornaments are your style, the Westin may be a good choice. If you prefer modern simplicity, and expect value for money, you should look elsewhere.

The good:
- Big hotel with accordingly wide offer of facilities
- Ebisu is a great place, and the Westin is the only major hotel
- The rooms are very spacious for Tokyo standards
- Big LCD TV, DVD-player, Fax and printer in the rooms
- Very comfortable bed and pillows
- Safe has an electrical outlet inside (great for iPods etc.)
- Most of the distance to the station is covered
- Mitsukoshi Department Store across the street

The bad:
- Maximizes turnover per customer (many services have quite a hefty fee - also see below)
- No nice views over the city
- Hotel is quite far away from the Station
- Small bathtub

The ugly:
- At a rack rate of 60.000 Yen, customers should not be charged separately for things you can take for granted, like In-room internet (1800 yen) and gym usage (1000 yen).

The Westin is a nice hotel, especially for lovers of traditional American style luxury, but at this price point, I do expect more perfection. You can have similar luxury at half the price (e.g. Strings Hotel) or get more perfection at the same price (e.g. Grand Hyatt)

I stayed here for a week in early March, 2007, and the entire experience was fantastic. I had the pleasure of being within the "Executive Club," which included a wonderful high-floor room (huge!); access to the executive club for breakfast and cocktails; and other amenities.

Ebisu is a great area of Tokyo, as well. A big high-end, great restaurants, amazing access to transportation, within a few minutes of all central Tokyo sights.

I visited the Westin Tokyo on a business trip between 17 Feb and 20 Feb and had a fabulous stay. As an SPG Platinum member, I was upgraded to a large room on the Executive Club floor. This room was large and elegant even by American standards, with a marble bathroom, HD TV, chaise lounge, couch and desk.

Unlike the previous reviewer, I found the service to be among the most polite and detailed of anyplace I've ever stayed. The turndown service provides freshly pressed pajamas and a kimono and the housecleaning folks are as close to perfect as I've seen. For example, the bathroom had an amenities kit with toothpaste, razor, etc. and every day the staff replaced every single item in the kit--and didn't just put it on the counter, they put it in the proper spot in the kit, zipped it closed and placed it in its spot on the counter. That's pretty amazing in my book.

My only ding on this place was for room service. I ordered a green curry chicken that was almost inedible--three very fatty slices of chicken, totaling maybe 1.5 ounces, all for a mere $30.

That aside, I would return in a heartbeat.