I stayed there a couple of weeks after it had opened - consequently, they only had a limited number of rooms available, no lounge etc.
But the hotel was fairly empty - got personal trainer service at the gym, as I was the only one there etc.
I don't have much experience of JW Marriotts (not in the locations I usually travel), but it certainly seemed nice. I was very happy.
The location is great, in terms of being next to the park in the centre - nice to have some greenery in Bangalore!
Any other specifics, would be happy to help...