I think something I enjoyed about Firewatch is that while it is a lot of walking and talking, it didn't feel as introspective as some of its contemporaries. I'm not too familiar with SOMA so I can't speak on that one, but it certainly doesn't fall prey to the same problems that games like Dear Esther or The Beginner's Guide had where the game is entirely about the narrator's recollection or discovery of something, and instead feels a lot more like a story you're an active participant in. Really, I think the comparison to Telltale games is much closer to how it feels, just in first person rather than the third usually seen from the typical "Walking Simulator" tagged game.
As for the voice actor, I rather like her, though this is the first game I've played with her in it, I think. Typecasting for certain voice types is unfortunately a thing in multiple mediums, though. I think the does very well in this one.