I didn't read enough praise about Shadwen in these forums. Need to change this.
First, I really love a lot about the game.
...this makes it really hard to start talking about it, though... :/
Let's just sort this into chapters, huh?
Idea
I don't know how you pitched it, but I imagine it like this:
"Yeah, I thought of a stealth game... you can just imagine it as Assassins SUPERHOT République of Time. ...and it's Bring-Your-Daughter-To-Work-Day. With a grappling hook."
All of that is awesome, but I especially like the grappling hook. You remember playing Assassins Creed, yeah, it looks super cool, but you only press two buttons to get from A to B? Grappling hook. Nothing more to say. So much fun, so much awesome.
Oh, yeah, and then somebody was like "Aaaaand do you know how we're gonna promote our demo?..." and then everything went crazy and awesome. (I still really wanna know if this "worked" from a financial/publicity view...)
Stealth
In short: It's the best implementation of stealth since Mark of the Ninja and, well, maybe a bit better. (It's 3D! :3).
To be honest, there are two major problems, I have with stealth games:
First, I don't have any idea what's happening.
You know this "Where was this guard again?" situation? No problem in Shadwen, since I'm usually on a high point. It's save there and I'm having a great overview. Since it's Bring-your-daugther-to-work-day, it is still challenging.
Second, I'm really bad.
You know this "Where was this guard again?" situation - and suddenly he's behind you. Game over, hope you like to see the start of the level again. No problem in Shadwen, just go back in time. "I just missed the sweet spot to sneak through. Now I have to wait two hours until this F***ING SNAIL OF A GUARD PASSES THIS POINT AGAIN-GODDAMMITMOVEYOURA-"*. No problem in Shadwen, just go back in time.
Because of this, I start to get reeeeaaaally cautious. Like, "sneaking in Crysis and only walk five steps, hide behind a tree to recharge your invisibility"-cautious. Not to mention, this is not really exciting. Well, just risk it. It worked? Awesome! It failed? No problem in Shadwen, just go back in time.
*(You know Velvet Assassin? Me neither. I quit it during the first level because of this issue.)
Animations
Shadwens animations just look awesome. I know, there is Assassins Creed. But damn, Altair doesn't have that fancy braid swinging around. I was a bit sad that I couldn't see the killing animations in my first (non-lethal) run.
(...okay, okay, I did see them, because "No problem in Shadwen, just...")
Since this thread is called "praise", let's just not talk about facial animation. It's not that important for this type of game, anyways.

Characters
Shadwen and Lily are super awesome characters. It's a bit like Of Orcs and Men, but much more believable.
Voice acting is awesome, they look awesome*, nothing more to say.
*(okay, at least in the artworks, ingame they seem a bit dorky

Polish
You know this situation? You are playing Assassins Creed, you want to hide in some straw (because that's what assassins usually do all the time), but your character is all like "Nah. I'm going to climb this building now.". In Shadwen? Go back in tim-... nah, okay not this time. I rarely had those moments. Actually, I found a lot of the opposite. This "Man, I bet they polished that level a lot, so I can just get jump around so smoothly." feeling.
Also the killing animations (the few I saw) never had this ugly offset bug, which we all know from Skyrim, AC, Age of Conan,... actually every game with killing animations.
Lilys AI is pretty neat. I mean, yeah, I had some moments where I was like "Lil-puff, what are you doing?!!", but those were rare. You know this , when you really want to kill your AI companion? Especially in stealth games, where every game-over-screen could play the voice line "Oh, we were stealthing? Ooops, I thought we wanted to mimic the rutting call of elephants!". So, what makes a good companion? You don't want to kill him/her. Lily doesn't alert guards and most times, she walks where she was told to. Sometimes she just runs back, because... well, little girls don't always listen, huh?
Traps
The ideas for the traps are pretty cool and you can play a lot with them-... I guess, since I didn't use too much of them, since I was playing non-lethal.
Maybe, let's not praise all the way and add some critique here. For a non-lethal run, nearly all traps were not very usefull. And traps are very limited. This gets you in this "Don't use it now, maybe I'll need it later" situation, where you rather slowly torture yourself through a tough part, instead of using a precious crafted trap.
On the other hand, praise be onto you for making the grappling hook and time reverting infinite.
Ending
Well, talking about critique... to me, the endings were unsatisfying.
First, most of the endings were just "Yeah, bye.". I don't wanna escort that little girl through trillions of guards to be like "Yeah, hope you don't starve now. C ya bb." Okay, Lil comes with you... but only in the merciful ending? Why is that ending better than killing nobody?
Also, the bad endings are (to me) faaar to unsatisfying. It seems inuitive, that be bad ending should leave the player with a bad feeling. And that it is a key challenge of the game to hide your identity from Lily. But a game can't give somebody, who played your game from start to end, a "second class ending". (Metro Last Light does this and... man, was I angry.) The ending doesn't have to be "Lily loves you anways". Maybe somebody who kill everyone does not care about Lily. But then give them a ending that says "Lily hates you, but damn, you're a badass killer. A king slayer. Like Letho from Witcher 2. So badass." and not "Duh. Play the game the right way, the next time.".
Some more things: The game spoils the ending at the beginning. I, personally, hate that. Buuuut, I was like "Damn, if they spoiled it, there has to be some major twist! I mean, everybody talks about dark spirits! Maybe this has something to do with Lily! Lily talks about her mom! Maybe she has something to do with the spirits! There are prisons, maybe Lilys mom isn't dead but in there! Maybe we can free her father...!".
But, as you know, there is nothing. :/
And this is really, really sad. I mean, every guard was talking about the dark spirits and the burned forest. It felt like you REALLY wanted to make sure, the player hears about that, because it might be important later. There is also much talk about the war, the famine and in the "killer run" also about other kings and the tale of the crow. Nothing of it seems to matter in the end. :/
If you have such a big backstory, please tell us more about it in the game.
Or, to say it some more optimistic: Your story made me super curious and got so much potential, don't drop it at the end.

Trailer
You asked about some feedback to the trailer elsewhere, let me just answer this here.

What I found confusing was that you didn't include some major things. Thinking about the pitch from before: Assassins SUPERHOT République of Time with a grappling hook. The trailer never shows the SUPERHOT mechanic, the grappling hook only once. Time reverting also only once at the end, and there it might just be some fancy video effect for the trailer.
You DO show a lot of traps. Like, more than you could ever craft in the game. I know, that you sometimes don't want to show actual gameplay in a trailer to get people hyped. But (in my opinion) you missed the part that got me hyped for Shadwen.
People like explosions, yes. But there are a lot of games with explosions. If I want some, I'd rather play Battlefield with Michael Bay worthy explosions.

Okay, damn, I'm at the end. But I can't end this post with a negative point... I mean, I love the game!
Hm, here we go: Did I mention that I crafted not too much, but I really loved the item descriptions?
I mean, I didn't open my inventory for the crafting, but to read the descriptions. It seems really insignificant, but it says a lot about the charm of a game. The voice lines, the art style, the beautiful settings or little lines like "Fresh apples, they are all yours!" or the item description - all of that makes you feel like somebody really put her/his heart into that game. And, damn, I bet you did.