I'll give this a go. I should say that I haven't played Adventures yet and I haven't read much feedback from people who have, so these opinions are all purely speculative and could be way off. I feel pretty confident about the skill level of some of these cards and utterly clueless about others. I might add more detail later, though I don't have a laptop at the moment, so typing long posts is difficult. I'll go by cost, listing from best to worst.
$2:
Peasant - Champion looks better than Teacher, but every card in this line looks pretty good. Teacher is one of my favorite cards ever.
Page - Champion is good but getting there is tough. Still, I think it will usually be worth it.
Ratcatcher - Not sure about this one. It looks pretty slow, but the fact that they don't get in the way at all, are incredibly cheap, and remove themselves from your deck once you're done with them could make them really strong.
Coin of the Realm - Good when it's there when you need it, but looks pretty unreliable. That being said, a village is a village.
Raze - Really unsure about this. At first I thought it was going to be terrible, now I think it might be alright, but I'm not really sure. I don't really like it, though. It's a TfB card which gives you virtually no incentive to trash really expensive cards, which I don't really like.
$3:
Dungeon - The benefit to your first turn is modest, the benefit to your second turn is huge. Feels like it should be better than Warehouse.
Gear - Looks tremendously flexible. Hard to see this not being a power card.
Amulet - Pretty good trasher. Silver-gaining makes it a nice BM card, too.
Guide - Good defense against discard attacks, good for cycling. Use cautiously, though.
Caravan Guard - Yeah, this looks really bad. I hope it's better than we think it is, but I don't think it will be.
$4:
Magpie - As others have been saying, this looks like a must-buy on almost any board.
Port - Village is good, so naturally double Village for 4/3 the cost should be really, really good.
Ranger - I really don't know how good this will be. I really love the card, though, so I hope it's good. I think it probably can be, though it probably needs a good amount of support.
Transmogrify - I don't really know. It looks meh to me for the most part, but undoubtedly it has the potential to be very powerful on some boards. Risky, though; don't turn your Village into a Smithy if the Villages are gone.
Messenger - Woodcutter and Chancellor are bad, and they don't really have much synergy. The on-buy effect can be useful, but the windows in which it is useful are probably going to be pretty narrow. Looks like a high-skill card, I like it.
Miser - I thought this looked really good at first, but it looks painfully slow, and you definitely need a lot of terminal space for it to shine.
Duplicate - This looks incredibly mediocre to me. Hard to imagine you'll want to spend a terminal on this very often. Still will be important when there's no other extra buys or gains, though.
$5:
Lost City - Super powerful. The penalty will hurt but will almost always be worth it, I think.
Bridge Troll - I won't be surprised if I'm overestimating this, but this looks incredibly powerful. Bridge is good, and this is a Bridge the turn you play it and a cantrip Bridge the turn after; and there's an attack! And it only costs $1 more than Bridge. And the attack looks pretty brutal.
Haunted Woods - The attack will vary a lot in usefulness, but that draw is insane. This is another card I may be overestimating, though.
Storyteller - Looks difficult to use, but very powerful on certain boards.
Royal Carriage - Throne Room variants are typically powerful, and this is no exception. Is also the first card that can allow more than 2 or 3 plays of a single card, and stacking these on your power cards could be really good.
Artificer - This card is so cool. It strikes a really neat balance between hurting your current hand by discarding and helping your current hand by topdecking a solid card. Will probably be really busted with draw-up-to-X.
Treasure Trove - Looks positively monstrous in BM. Probably bad in engines that aren't built around Watchtower or Storyteller, though.
Distant Lands - Looks better than I initially thought. Giving up terminal space for a one-shot that gives a pretty significant amount of VP seems like a generally fair trade. Is probably atrocious in BM decks, though.
Wine Merchant - At first I had this listed as the worst $5 card, but upon further consideration it's not as bad as it might at first seem. The key is that you can discard any number of these at the end of your Buy phase if you have $2 leftover. This means that if you can play multiple per turn (including with TR variants) then only one is equivalent to a Woodcutter, and the rest are as good as a $5 action that gives $4 and a Buy (which is pretty damn good). And, while it's probably usually better to discard it the turn you play it if possible, having the option to hold onto it and sacrifice the $2 on a later turn is nice.
Relic - A $5 Silver is pretty bad, so the attack better be pretty good. Unfortunately, I'm not convinced that it is. It doesn't look bad, just not that great.
Swamp Hag - Probably better for the money than for the attack, honestly. Will probably have niche uses, but overall looks weak.
Giant - The token-up effect just doesn't seem strong enough to warrant making this card a terminal Copper every other play. Seems really bad, though could still be relevant in the absence of other junking attacks. I don't know.
$6:
Hireling - Looks fine. Kinda slow, but the benefit is huge. Will probably be a medium level card overall.
I may do events later.