Excellent service, wonderful rooms and Hermes bath products. I recommend the tasting menu at Vivendo.

We enjoyed 5 nights at the St Regis this past May.

On the plus side:
* bedroom was lavishly decorated and furnished
* the room had excellent internet connection (E15 per day)
* the bed was superb
* the linen was superb
* the shower was superb (as were the bath products, all Hermes)
* hotel bar and public areas are stunning (a vast fortune must have been spent recently on renovating this grand old dame of a hotel)
* hotel barstaff delightful; cocktails reasonably priced
* concierge and other staff were all helpful, friendly, and courteous

On the negative side:
* breakfast was not particularly imaginative
* the location is not ideal for vacationers, as it is a fair walk to the usual spots (Spanish Steps, Pantheon, Via Veneto etc); we visited the Russie which has a fabulous location
* there is no outside public space, so on a sunny day you are stuck inside (again, the Russie by comparison has an attractive garden - but it is much more expensive)

Recommendations:
* if possible, get a bedroom facing inwards; the road noise at the front of hotel is quite considerable
* consider using taxis; by London standards they are remarkably cheap, and because the hotel is a bit out of the way for tourist activities, they save a lot of shoe leather
* consider booking art/cultural tours with [------] - expensive but wonderful

Just returned from a 10 day visit to Italy with my wife, staying in Rome at St. Regis. Here is the real scoop (this is not a review shill placed by the hotel). This hotel is old, but very nice by European standards. Rooms are nicely decorated, but SMALL by American standards-I still am trying to figure out how they look so large in the pictures, because we could NOT get the camera angle from any location to make them look that large. They are NOT the Westin Heavenly Beds, but they are not uncomfortable either, just not the same as those great Westin beds you get in the USA. Bathrooms are also small, but nice and very functional (opt for the separate shower in your room if you can, they are great). Location is quite good, right near Via Veneto and all the shops, and a nice walk to the Spanish Steps, Trevi Fountain (15-20 minutes). The hotel provided us with a fantastic guide who spoke pretty good english, to tour the Vatican, St. Peters Basilica, but the concierge is going to recommend the most expensive guides (everybody has to get paid!), so if you can get a recommendation from a friend, you may want to save some money that way. Their guides are $80 Euro per hour and you definitely do not want to do a walking tour, so they can arrange a Mercedes w/driver for another$40 Euro/hour In either event, get a guide that can get you into the Vatican and the Collusium without waiting in lines or you will regret it.
Food at the hotel is way, way too expensive-YOu can eat great meals at Piazza Novona for 1/2 to 1/3rd the cost, and it is more fun. The dining room is spectacular however, just not that great and too expensive.
The concierege was helpful, but didn't rush to help, we had to kind of push ourselves to get his attention, and then he attended to us nicely. Overall would stay again at this place but might try the Westin Excelsior just up the street next time just because it has a little bit better location and is in a little less busy area

We had a fabulous 4 night stay at the St. Regis in early May. Our junior suite was absolutely gorgeous...beautifully appointed and the bathroom was a dream. The butler service with our coffee delivered each morning with a wake-up call was something we could get used to! It was so nice to return to such luxury after a long day of sightseeing. Our one mistake was thinking it was walking distance from the termini...bad idea! Next time we'll take a cab. Our thanks to this forum for guiding us to this wonderful hotel!