Well... i just viewed the topic and i'm kinda glad we re gonna have a new expansion. And all the cards seem interesting. Now, i just want to display my opinion about some cards.
Masterpiece:I noticed that some people didn't really like the card. I believe it's very good on certain decks.
It's obviously a very good slog card, but other than that - guys, Big Money!- it can be good on a BM deck when u just don't want to buy anything else for $4, or $5 and this is a very good way to kill underbuys. What you basically do is that you buy a copper accompanied by 1 or 2 Silvers, but before you guys jump to say that coppers are bad in BM decks, i want to remind you that in this kind of decks the percentage of treasure cards vs victory cards in your deck matters a lot. So, unless there are handsize reduction attacks, Masterpiece can help a lot in BM decks.
(Actually, maybe it's not worth buying a Masterpiece for $4 in BM unless it's late game, but for $5 it can be worth it.)
Another use for Masterpiece, in my opinion, is to gain cards to TfB. Apprentice and Salvager will like this card, i believe, as you can pay $4+ to gain 2+ cards that cost $3, thus provide "easy" fuel for them. I already like to use Trader for this purpose and it works nicely for me. Masterpiece will make this job even easier.
Plaza:I have been working on draw-to-X engines lately, and Plaza is a nice addition to the card roster for this job. Discarding coppers for +coins is just what you need in draw-to-X engines and with Plaza, you can do it while gaining more actions (unlike horse traders or oasis) and the fact that you can choose whether to spend the coins this turn or another one makes it a really good card for this job.
Taxman:This card looks really interesting and seems somewhat better than Mine to me. Even though, you don't get the upgraded treasure in your hand, it is put on top of your deck so it's ready for use immediately. The attack part is very important, especially early game, and unlike Cutpurse, the attack will still hurt late game. Overall, it's a very strong card relative to its cost, in my opinion.
JourneymanNow, this is a nice drawing card. It has about the same use as Catacombs, but works more like a Hunting Party (as regarding in cards being skipped). Can be very strong early game for skipping those coppers or estates along with giving you 3 more cards in your hand. I wonder how Journeyman-BM would be like...
EDIT: Oh my God! just noticed!
Combo: Journeyman - Tunnel !!!
I will steal the words: "Just name Tunnel..."