The routing is the most intriguing part to me: I'm not sure yet if it's any better than the alternatives of VCV-style visual wiring or a Thor-style mod matrix, but its distributed mod system is a different approach to synthesis UI and worth a look.
It's currently in early beta (there are enough warnings about stability that it sounds more like an alpha), but if you dare, you can download it here: https://www.fullbucket.de/music/modulair.html