I just finished Echo a few minutes ago after about 6-8 hours of playtime. I kind of have mixed feelings about it, but I'm mostly happy with my experience. I would give my playthrough an 8/10.
I'm seeing in the other comments that every character seems to have their own route, and I haven't even seen half of the screenshots on this page during my playthrough. I played through Leo's route, but I'm excited to try the others!
Positives: The writing is superb as I've come to expect from EchoProject. The spookiness and tension are really effective. It's a real "page-turner". I felt like the characters were all interesting and unique with their own personalities. In VN's, a lot of the time the choices don't really change a whole lot, but in this game, it seems like your choices have a really big impact. The illustrations are incredible. There are parts of my playthrough that made me sick to my stomach, which is really great for a horror story. The music and sound effects are really nicely used. The UI is also really unique and clearly a lot of effort when into it.
Criticisms: I wasn't really "satisfied" with the ending I got, unfortunately. And I felt like there were a lot of questions and interesting things brought up, but that never got answered/resolved. The game being in 480p took some time to get used to. I didn't mind the fact that the backgrounds just seemed to be real photos with a painterly filter on them, but it did take away some of my emersion when the background lighting did not match the time of day as it was described in the text, Leo's bedroom being one of the biggest culprits. Also, like 3/4 into the game, I started seeing a lot of spelling mistakes.
Comparing this to Adastra is not really possible, and I've only done one playthrough of Echo, so my opinion might change later. I'd say in terms of atmosphere, this game is stronger.