I am looking forward to the first reviews on FT regarding this property. When having walked by (and staying at the Hilton Berlin) very late December 2012 there was no sign from inside that it would open soon. However, around New Years Eve the hotel was open to the public to view rooms and public spaces, as I read in the news paper.
The W=A and Hilton are not close together. The Hampton and the W=A are. The Hilton is situated in the historic city center (Berlin Mitte) which was in post war East Berlin. The W=A is in the city center west, which has become cultural, intellectual (and entertainment) center between both World Wars. This area was the city center when the city was split into east and west. It was somewhat neglected nowadays but this apparently changes. I personally like the area a lot. Most likely the room charges AND the lacking benefits for hhonors members will keep me from staying in the W=A. Otherwise I am happy that it is open now.