Played 4 games with 3 kingdoms using all three of the new cards tonight in each kingdom. Here were some things I learned about each card:
Poor House: This card was super fun to play with. I generally observed that this card has some great combo potential, especially in a deck loaded with actions and Throne Rooms (or King's Courts). Heavy trashing helps this card immensely, and its flexibility is fun. This is also especially good with extra buys and shines with Bridge.
Sage: Something I didn't expect is that Sage is a fantastic counter to Ambassador, more so even than the enabling that an opponent gets from having Sage to play their Ambassador more often. Sage is easily my favorite of the new cards because of its ability to give you a key card to your engine reliably. Sage makes it especially tempting to bypass Silver altogether.
Graverobber: This card was extremely situational. The first 2 kingdoms didn't see this card played at all, but it was amazing in the last one (which we played twice because we liked it so much). Throne Room, Remodel and Feast with this card were all pretty awesome.
Here were the key cards is the kingdoms played:
First game: City, Bridge, Herbalist, Talisman, Fool's Gold, Sage, Poor House.- We just messed around and played with the new cards.
Second game: Minion, Ambassador, Menagerie, Lighthouse, Sage, Poor House. (This game I did an almost mirror match, with both players taking a Minion based strategy. One player played Ambassador a bunch more (due to shuffle luck) and the other ended up play Menagerie and Sage to counter. Menagerie/Sage won out in the end by the estates passed with Ambassador).
Third game: Throne Room, Sage, Great Hall, Graverobber, Poor House, Remodel, Masquerade, Feast, Courtyard (Witch was the other card, but nobody took one). This one was fun! We played two games with this kingdom. We both ended up using the Throne Rooms like crazy with Sage, Feast, Poor House (since we wiped out all the copper and estates with Masquerade and Remodel) and especially Graverobber. I would recommend this kingdom to anybody to try out these new cards.