Adventure Mode is in pre-Proof-Of-Concept stages. You can't walk 4 steps without hitting an "under construction" sign. Most of the problems you run into are just things that aren't implemented yet.
Naturally I don't hold any of the weirdness that crops up in adventure mode against it (ditto for fortress mode). It's been said before, and I agree, that all of the absurdity and madness give DF a lot of charm. I had actually played a lot of DF2010 fortress mode and become accustomed to the game's quirks. However, I only messed with adventure mode a little before this release, and all I had done was make generic adventurers and run the prescribed quests until I got an unlucky round and wound up dead or maimed. So, the only thing that really threw me for a loop in all this was hearing that non-historical NPCs just keep re-genning with the town (mostly since I'd heard of adventurers depopulating the world and sending it into the twilight era before).
Oh, and also walking through the door and insta-decapitating that tanner was hilariously surprising. My brother and I had a laugh trying to come up with a plausible in-character explanation for that little event. I would have done the whole post from the adventurer's point of view, but for the fact that we never really thought of a good one. As a result the whole thing turned out kind of half-in and half-out of character, with my ignorance as the player somewhat embellished. Truth told, I was only going over to that first house to check if the town was hostile to me after attacking that dog, and I kind of expected they would be after having to confirm my attack (although you have to confirm attacks against neutral wildlife as well). Everything that followed was me acting as I thought my rational adventurer might.
Anyway, it only takes a little meta-thinking to form expectations about how the game will respond to most actions, and there isn't a whole lot of adventure mode content yet, so it can be pretty boring to play things the way you're expected to. However, as I've found now, there's some real fun to be had in adventure mode, just follow these steps:
1. Forget meta-thinking, get in character and do something the game isn't designed to handle yet.
2. Try to play it out like a rational person would.
3. Laugh as the madness rises.
4. Post it on the internet for others to enjoy.
Of course, things won't always be this way, since Toady's stated(?) goal is almost the antithesis of this method of play. In the final release, players will enter the game with meta-expectations borrowed from other games/past experiences, only to have them exceeded and shattered by the extreme nuance and detail put into the world and its ability to realistically handle your character's actions. It's an admirable goal, I think, but the game is fun either way.