I greatly enjoyed playing this VN. I think this game was well-made. Each of the different routes does a good job of providing a different plotline and experience for the player. Every route sheds light on a different aspect of the town, the characters involved, their pasts, and their relationship to one another, leaving the reader engaged and wanting to play each route to learn more.
I think that the plotlines of each route were well-written. The routes each have their "WHAM" moments where something is revealed that totally changes one's perception of the characters, or things go from 0-100 real quick. TJ's route is an example of this, and the last few scenes were shocking due to how quickly things escalated. I did not expect that. These revelations also help keep the reader engaged, and definitely left an impression with me.
This VN deals with some heavier themes such as trauma, abuse, drug use, and suicide. It does not pull punches in that regard.
Echo does a good job of creating a tense atmosphere when needed through the use of music, dialogue, and its art. One part that really stood out to me was when Dark Chase just walks onto the screen, all animated and such, in contrast to how characters in Ren'Py usually come and go. That was pretty unsettling, well done.
Although there is a fair share of romance in Echo and there are a few sex scenes that are written out, but not shown, I think that this game can be enjoyed both by furries and non-furries alike.
I liked the game's soundtrack, particularly circles3 and the theme that plays whenever action takes place.
As far as things I didn't like go, there are a couple. In Jenna's route, Flynn and TJ stumbling upon the characters towards the end and the train that the group boards at the end of Leo's route just happening to be the last of 3 trains that were being moved to a museum seem like a plot contrivance, though, to be fair, that one is foreshadowed throughout Leo's and other routes. However, these things occur towards the very end of their respective routes, so they don't ruin the reader's engagement with the story that much. One MIGHT argue that the monster saving the characters in Jenna's route was a Deus Ex Machina, but, given what is revealed about it in other routes, it makes sense from a story perspective. The part where Chase is saved from the mines as he was about to get shot by Brian is a bit iffy in that regard. Maybe it's something that is going to be explored in The Smoke Room or Arches?
TL;DR: Great VN. There are a couple minor things I didn't like, but overall, I would recommend this.