I had an award stay at the Bentley quite recently. I had stayed there quite often in its Kempinski days, until a series of problems sent me away.
I was upgraded to a full suite (and I'm a mere HH gold), but all the single rooms I had in the pre-rebranding days were a very good size, as were the bathrooms.
The hotel seemed much the same to me--a similar air of slightly faded grandeur, reception desk moved, doormen more present. The staff in general seemed very accommodating. My greatest sorrow was the disappearance of my favorite Penhaligon toiletries.
While Gloucester Road in the immediate vicinity of the underground is not very pretty, I find it a very convenient location, love the Waitrose, and appreciate the proximity to three very useful underground lines and the quick walk to South Ken.