I also love the notes that some of them are carrying - for example, the one at Cloud Top warns the assassin to absolutely not touch or try to read the “Fingers of the Mountain” book. They’re a difficult, though not impossible fight, and some of them have nice loot.
The assassin locations make sense, but are still random enough to keep me surprised. The mod does exactly what it says it does, and it does it well almost all the time. If you continue reading, you’ll encounter some minor spoilers, so be aware of that. The TL DR: This mod adds hostile Dark Brotherhood assassins throughout the world, and I love it.