Previews are out and I missed it.
Time to catch up.
Most of the things were probably already mentioned, but I just mention what I notice.
At first the card seemed boring, too vanilla, but the more I thought about it, it's a great card and I'm excited to play with it.
I think Baker is much stronger than Treasury and Market, not a power $5 though, but for certain above average, maybe on par with Highway if you compare all those Peddler variants.
Saving coins is a huge benefit, more than some people might realize. I think it will fit great in both engines and BM-ish strategies and will perform similar to Bandit Camp which might be the most comparable card. Pure Baker-BM is probably not super strong, but on weak boards still not ignorable, I think.
Let's have a look at some interactions. The virtual money might be good in getting to Grand Markets as you can buy one with 2 Silvers and 2 tokens now. It's of course great with Tactician as you can play it when you discard your hand and save the coins for later. I think in slower games with strong attacks it might be pretty good too as you can play it after were hit by a Ghost Ship and save the coin for later. In cursing games you can get to crucial cards and late Provinces also more easily. Although it could even out the money in Duke games, I don't think it will be great in Alt-VP games as it has a high opportunity cost. Maybe one copy early is great, though. Still, this makes it a very good versatile card in general.
Now about the setup instructions: Wow, what a game changer. It has a great impact to the game and especially to the opening buys although you might end up never even buying it. Now you could open $4/$4, so maybe Double Sea Hag, and wow Double Treasure Map, maybe even Double Potion on a Scrying Pool or University game. What do you think about double Remake? Also, you are guaranteed a crucial $5 with Baker on the board (with Baker probably not being one itself) and aren't screwed with no $2s on the board. Also you could now open with Goons, Altar or Hunting Grounds or Hoard and of course Gold!
Even after one card spoiled I agree with Donald X. that this seems the most skill-intensive expansion. Let's say you have $5 and at least 3 coin tokens. Do you buy another Baker, a Gold or a Province? For that you have to take into account the composition of your deck, your position in the current shuffle and the current turn number. I like that focus in skill although I dislike that games with Baker or other coin token cards will or might slow down games as you have so much more options each turn.
Other stuff: The art is horrible (sorry!) and the expansion icon is a sextant (?). Maybe a card named Astronomer will come out!?