I think Mary Shelley, the author of Frankenstein, chose to lead into the stranger's story with Robert Walton's letters because it makes you wonder who is this Robert Walton person, what is his importance to the story, where is Frankenstein?, and how does it tie into the story? I think she also wants you to make connections. It makes you wonder and want to read on further. Though the language is hard to understand at some points, it does make sense. I have only read up to the end of chapter 1, and when Frankenstein starts his story it is pretty interesting!
My impression of the book so far is boring, but I'm sure it will get better. I don't particularly love or like this book at the moment, but I think I will once it gets more interesting. The reasons why I don't really like it at the moment because it's not fast paced or "mind-blowing", it's kind of slow. I think most books start out slow though because you need background information and all of that. I think I will end up liking it tho, I heard it gets good. I'm excited for that.