I've been inspired to read more Orwell since I started teaching two of his essays, "Why I Write" and "A Hanging," on a regular basis, and I must say, it's a rewarding experience. My friend Russ had told me that this book (which he very much admires) is about how petty differences can divide groups that are struggling against a common enemy (I believe we were discussing liberals in the US at the time). It's interesting, in that while I see how one could read the book and take that away from it, that hardly seemed central to me.
Orwell's writing is wonderfully crisp and vivid. You really do feel as though you know what it's like to be there in the trenches beside him. In "Why I Write," he talks about how he loves description, and would have been content, in another age, to write poems about flowers, so it's not really surprising that some of the most wonderful parts of this book were about mud. I particularly enjoyed the description of getting shot - fascinating stuff. Apparently the bullet basically kills surrounding nerve endings, so the bullet hole itself doesn't hurt, but whatever other damage it causes very much does. Orwell has this way of addressing the reader directly, but without any smugness or self-righteousness. It's extremely appealing.
As for the story itself - I know very little about the Spanish civil war, and to be honest, most of what I got out of this book is how very difficult it is to actually know something about it. Orwell really emphasizes this - how murky and unclear things were, and especially, how inefficient the spread of information was. Quite a contrast, one imagines, to modern day warfare. At least, one hopes. One of his major points throughout is that journalists completely misrepresented the whole thing (because they often didn't know what was going on, and were reporting second-hand information) and actually exacerbated the conflicts, turning various sides against each other. He registers his outrage over what seem like senseless deaths (he does not see death on the battlefield as senseless), but without getting overly hysterical or melodramatic (it's quite an English book, in that way).
Basically, if you're going to read one book about the Spanish civil war, this is not a bad choice. If you're going to read one Orwell book, this would not be my first pick, but it's nonetheless pleasurable.