Thoroughly enjoyed our visit here in December 2012. Would recommend anyone visiting in the winter - it was so quiet we almost had it to ourselves. All the rooms were available to us, which is not usually the case. The decor is fascinating and astonishing to see. Pity you cannot take photos in the amber room, but I suppose they have to make money selling you a picture (10RUB - which was not that expensive for a post card).
Would recommend as a must see attraction on a St Petersburg visit.