At this point I think we can all basically agree that every game that Wadjet Eye releases is going to be worth buying right away. This is Dave Gilbert's first game as lead designer since Blackwell Epiphany. There is overlap with the Blackwell universe, but it is definitely a departure from those games.
Possibly taking a lead from Telltale, there seems to be a more deliberate attempt to make your choices affect the story. This manifests itself first in that you choose one of three origin stories for your player character. Then, throughout the game, each chapter ends with you deciding the fate of an adversary. The consequences of your decisions don't really ripple throughout the game. They mostly affect the end-game sequence. Still, it's a worthy attempt at adding a little variety to the experience.
The farther an adventure game gets from being a pure puzzle-solving endeavor, the more these types of ludic story-telling tropes become important. For the record, the puzzles of Unavowed are not very puzzley at all. In most cases, the path is pretty clear and, if there is any doubt, just talk to everyone, including your squad-mates. The game is mostly a matter of understanding the abilities of your friends and using them appropriately.
But all this is moot if you are just willing to sit back, click away, and let the story develop. There's enough good story-telling and pretty visuals there to make it worth your while. However, I don't think all the effort that went into creating branching narratives will really justify multiple plays. At least not for me. I think I'm fine with just turning on the commentary and racing through a second go-around. You know how much I love hearing about color theory and how voice actors are the salt of the Earth.