I stayed there this week and was impressed.
Great location for the City of London, close to Bank station, on a relatively quiet street. My first impression was good. Lovely entrance hall and public areas with a fantastic domed glass cupola ceiling. Low desk for check in with seats for guests.
I was upgraded to a suite which was very nice although not as large or grand as suites in some other London hotels. Bedroom with separate sitting area, nice bathroom with shower and tub. iPod dock and Nespresso machines also available.
No lounge but at check-in I was asked if I wanted still or sparking water and a large bottle, along with a bucket of ice and glasses was waiting for me when I came back to the room in the evening.
Breakfast in the restaurant is to order and the grill I had was excellent, although being made to order, it did take a while to come and if I had been in my usual grab and go breakfast mode, I would have been unhappy, but fortunately I did have time to enjoy the food and surroundings.
In summary, it isn't my favourite London Marriott (I'm torn between GH and RStP there), but certainly somewhere that I'd stay if I needed to be close to the city.