So, this is the prequel to Skellig. I went into this thinking I would probably be rather disappointed.
Instead, I found myself genuinely enjoying this. It's basically from Mina's point of view (the girl that Michael meets in Skellig) and kind of a journal of her thoughts and experiences. It was really, really well put together, even if it didn't seem like there was much happening occasionally. I wasn't bored by a single page, and the imagery was very clear in my mind.
I liked this book almost as much as Skellig. It was really wonderful and you got a really good idea of what Mina's life was like. Yes, there isn't really a plot. It's just her going about her life, but to be honest I could read 500 more pages of this and would still love it. The pages are punctured by her quirky little phrases and thoughts about life, and quite a bit of it resonated with me.
So yes, I would definitely recommend this if you enjoyed Skellig. Near the end of the book, you realise how this connects to Skellig. That's really the only link as a prequel there is, actually - the fact that it's Mina writing her thoughts out on paper, and that it gradually ties up into meeting Michael. I love it.