I finally made it to the Gallia and the breakfast is indeed a step above other breakfasts at Starwoods I have had (in Milan or elsewhere), if not quite at the level of the Principe di Savoia down the street. My Signature suite is a nice space if a bit of an odd layout (lots of hallway space and a smallish sleeping area) relative to Junior suites at the Westin Palace. The high tech lighting etc. takes some getting used to but is a definite step forward and the wood floors are a nice touch. There is also much more attentive service than at the Westin though there is not yet the confident sense one gets from a longer-established hotel.
All in all I am enjoying my stay and if pricing permits I will stay there again.