It's the later, most of the time the interaction is limited to "press A to move forward" (i.e. no left, right or back option) or "click anywhere on screen to go to the next scene".

So the reason they made a trailer that showed nothing of the game is that there is basically nothing to show?

Hm, tempting... Personally I would have liked a little more visual detail, especially in the characters. But the general theme and style of the game look appealing.

Just how limited is the gameplay/ player interaction?

... wow, all right. The trailer really is pretty useless. Note to devs/publishers: If all you're doing is showing off assorted praise from gaming websites and critics, you might as well do it in plain text form. People don't watch trailers for that.

By the way, does the game have voice acting?

My kind of game, and set in my home state. That's an instant purchase right there.

Huh. Well, I'm leaning more and more towards the "wait until it's discounted -80%" option :P Thanks for the warning!

That's great news! I've been waiting for it and just got it.

The game doesn't have any dialog.

You mean neither voice acting, nor text based dialog?

Yes you have neither, that's one of the gimmick of the game.

I take it you've already played it? Did you like it? What exactly makes it worthwhile? I mean, when you take a detective/ crime adventure game, remove most of the gameplay, the dialog, and reduce the visuals to a stylized minimum, you're not exactly left with much.

According to the demo (and reviews on steam) very much limited. The game is more like a visual novel with tiny interactions to proceed from A to B. If you are not into the story, the setting and the atmosphere you won't get much here. Play the demo to be sure that you like it. To make it clear: I will buy the game and I am looking forward to it but I am also more into the story than gameplay (well a mix of both actually but I can live with not much gameplay if the story or the setting is really intriguing which is the case for me). This game definitely is not for everyone.
Atmosphere, mystery, suspense, not knowing what comes next and trying to figure out what it all means because of the cryptic scenes. Like a David Lynch movie actually.

Sure, but without any real interaction, puzzles, dialog choices etc., you're really just left with an animated film of questionable quality, at which point you might as well watch a traditional film instead, which probably does a better job at all the aspects you've listed. And I'm saying that as someone who has enjoyed various "walking sims" ( Ethan Carter, Kholat ) or modern adventure games with limited interaction ( Walking Dead etc. ).

Anyhow, I'll wait for a few more reviews before I make up my mind about this one. All the info about the game, including the pointless trailer, left me somewhat skeptical. Worst case I'll pick it up at a higher discount some time.

I already told you: just play the demo. It gives a pretty good picture of what you can expect from the game. Since the game is 90% (stylized) visuals (no speech like already said) it's better to see by yourself than letting describe why it could be worth it. I did not play Kholat yet but I would hardly refer Ethan Carter as a Walking Sim because it has real puzzles in it. Walking Dead is more like it but it has QTEs and choices. This game would be more like a walking simulator than the the others you listed. Why not seeing a movie? Why do people watch visual novels? It's sometimes the different kind of narration the few possibilitys only interactivity gives you to make the story a different experience. Again: hard to describe.

Frankly, I'm not sure I want to bother with downloading and installing ( and later de-installing ) a demo for such a relatively small ( in terms of download size ) and cheap game. Even less so when the demo is apparently Steam exclusive. I'll just wait what other GOG users have to say about it.

As for Ethan Carter, it depends on who you ask, and what their definition of "Walking Sim" is. For the record, I did actually enjoy the game, and thought it had a few cool features, in terms of presentation and gameplay. But the main focus was clearly on exploration and atmosphere -- or in other words, walking around. The puzzle elements were fairly sparse and minimalistic, compared to traditional Adventures.

And I'm not even sure what genre TWD belongs to. TellTale have developed their own sub-genre of Adventure games at this point.

That's the point -- the more interactivity you remove from the medium of video games, the more it loses its unique appeal. Does this game even have alternate endings or branching story-lines, or any other meaningful way for the player to interact, and make an impact on the way the story progresses?