Sorry to interrupt the very important discussion about Elder rules, but I'm giving my thoughts on the power level and implications of the previewed cards, based on no testing whatsoever.
Town Crier can do the Pawn thing where it's sometimes a cantrip, sometimes something else. But I dunno, in modern Dominion, Pawn is kind of weak except for the +Buy, and Town Crier doesn't even have that. It's not very strong but it doesn't hurt either, and there's that Elder synergy to look forward to, so eh?
Town Blacksmith seems more like it. I think terminal draw that optionally cantrips is good in a way that Town Crier is not.
Miller is the super Border Guard. Eh... it's not bad, but do I really want to spend $4 on it?
To gauge the power level of Elder, rather than imagining, e.g. Town Crier but with two options, I credit the second option to Elder. So if I collide Elder+Town Crier, and use the extra option to get +$2, then Elder was like a non-terminal $4. I would rate this on the level of a nice synergy, hardly world moving. One thing that I find interesting, is that Elder synergizes with the top two Townsfolk, but not so much with Miller, so you have to invest in that synergy early and hope it pays off later.
Town seems somewhat above average for a village. It's a decent even before you get your action density up, and the +Buy will be appreciated when it's needed.
Modify is roughly the power level of Upgrade, but I think slightly weaker.
I'm not sure if this was answered yet, but for Band of Nomads, can you only spend one favor per card you gain, or is it multiple? I'm guessing it's just once per card? When I first looked at favors, I thought they might be about as valuable as +Action or +Buy, and Band of Nomads makes that fairly direct. But having the choice makes it even better. What makes it less good is the timing restriction. I think it's decent if you can gain cards during your action phase, but may otherwise be mediocre.
Architect's Guild seems comparable to Crafter's Guild from day 2. Well, it can gain more expensive cards sometimes, but not victory cards, and it doesn't topdeck them. I rated Crafter's Guild as extremely strong so I say the same here.