I liked this book a lot. The plot is varied enough to keep things interesting but it's very leisurely and there's no real peril or high drama. It's more character-driven than anything. Luckily, I adored the characters - it was a real mixed bag of folks and there was a nice contrast between the smart, slightly hard, London crowd and the group of oddballs from Guernsey.
Fact: I never realised that the Channel Islanders had such a rough deal during the Second World War. I knew that they were occupied by German forces, but I had no idea that many of them were on the brink of starvation, or that they had literally no news from Britain for nearly five years. Five years! Let's just take a moment to think about that.
I'm not usually a huge fan of epistolary novels, as I find it too hard to imagine what is going on behind the letters and I find it an oddly impersonal way of writing considering that letters are such an intimate item, but in this case the format absolutely worked and in fact I couldn't imagine what the novel would have been like if it had been written in normal prose.
I would completely recommend this book to anyone. I finished it a couple of weeks ago and even now when I think of it, it gives me a little warm glow.