Great story, great art, great characters, great voice acting. I was sad to see the game end. It's of proper length and it has a satisfying ending and I hope it will get a sequel because I got attached to the main characters and would love to see (and hear) them again.
It has varying forms of puzzling which never bored or frustrated me. I glanced at a walkthrough a few times to hasten a few things up which I didn't get right too soon, but I believe everything is solveable perfectly fine if one isn't in a hurry and maybe uses a pen and paper to sort some stuff.
A good thing: Throughout most parts of the game you can press a button to have things you can interact with in the world get highlighted. It helps those who don't want to look for "hidden items". It's not mandatory so those who love getting their full classic adventuring way can have it just as well. There is also a "combination helper" that, when enabled, puts a glow on your cursor when you hover with one item over another or over a spot in the world which it interacts with (though it seems towards the end it is sometimes isn't working fully either, intentionally or by accident).
The story could have some logic loopholes, but I need to think some details over because things can get convoluted with various characters looking differently at events throughout different timelines and sharing their (un)knowing amongst each other.
A downer: The English text and English voice acting aren't always aligning. Sometimes something is said but something else is written. In a few instances I had text or voice lines appear from previous scenes that made absolutely no sense in the scenes I was in at the time. One line (well, it was just one word, but still) was skipped away quickly even though I didn't press any button at all. There is a background journey "log" of sort you can look up and I noticed one text part not existing at all in the English version (it isn't just lacking translation - it's really simply missing, you get an empty subwindow when you try to read it in English language). These things don't happen too often, but they aren't exactly rare either.
However it's possible the English voice acting is better than than the native one. I played the game in English because I'm used to that but glanced at the German version because the developers are from Germany: It's by no length bad but in direct, short comparison I liked some important characters better English voiced. But I could be biased because, as I said, I played it mostly in English.
I noticed a specific scene that has significantly deviating English lines. The basic idea is still there, but there are some implications which are more direct in the German version. Could be that it's different in English because these are sexual implications. I hope the English version didn't shy away from the German original too often like this because as much as I like this game I don't think I'm gonna replay it in German anytime soon.
Also, that journey log - it looks kinda nice, but it's not very handy to use. It's a wall of images that get added over the course of your journey with some logical lines connecting to the images back and forth. You click on these images and lines and get some info on what happened (which is appreciated because the story can be confusing at times). However some parts of this image wall one may look over accidently because there aren't always clear cuts between the images and connecting lines.
It won't hurt to know the prequel "Chains of Satinav". The title "Memoria" is unfortunate as it should be "The Dark Eye 2: Memoria" to make clear that things happened before. This is an independent story, but one of the main characters and his female companion clearly had a long journey of their own before this, there are some references to events that happened back then one may understand and relate to better when having played the prequel first. I can't tell right now because I haven't played Chains of Satinav yet. The English voice acting is very great at showing that these two feel a lot for each other and went through a lot together, though, so it could be very well a positive aspect because it wants me to play Chains of Satinav soon.