First, I have to mention how bizarre it felt to be reading a book touted as being on National Review's list of the top 10 nonfiction works of the 20th century.
Prior to this, my only exposure to the writings of Orwell had been Animal Farm and 1984, so I think I can be forgiven for getting blindsided right at the beginning. As it turns out, Orwell was rather fond of the idea of working class revolution(hence the increasing confusion at the National Review endorsement), and in fact joined a Marxist militia to fight the fascists. This touches off 200 pages of reminiscence about six months fighting in the early part of the Spanish Civil War, a conflict that I had had only a perfunctory education on up to this point in my life.
This was a very interesting book to read in terms of style and also timing. Orwell account was written shortly after he returned to England, and therefore at the time he's writing the war isn't close to concluding, which changes the emphasis of certain ideas in the text. Thus, Orwell presumes that his audience is English and has been exposed to the war coverage being offered by various newspapers with ideological leanings, and therefore feels justified in devoting several substantially long passages to ripping on various international newspapers.
Another interesting aspect is what I would call the "dear reader" style. While Orwell never actually uses that phrase, he occasionally implores the reader or points things out to them about the text. The most curious of these, to me, is when he points out that the next chapter is going to deal exclusively with the factional politics within the "republican" bloc, and therefore readers that are uninterested in that material will want to skip the chapter. This especially baffled me because the rising tensions and aggressions between those blocs are critical to Orwell's story: while I can't say that it makes no sense without that understanding, it probably does makes less sense.
The last and least interesting of these anachronisms is occasional asides to discuss national cultures, especially the Spanish national culture. IE Spaniards are generally lazy and laid back about things, their food is universally drenched in olive oil, they were all bad soldiers, etc.
Beyond that, Orwell knows what he's talking about and provides a wealth of information about the fighting, the conditions, and the factional strife. He also manages to convey the feeling, very appropriate to a civil war, that neither side was actually "right" or "better". The fascists are more maligned generally, but they only appear on the front lines, and Orwell does show sympathy for the poor conscripts that had to serve for them. By contrast, Orwell shows the evil of the Stalinist party(that was increasingly influential within the government) and an out-of-control police force in considerable detail, as it was these parties that were ultimately more threatening to him than poorly armed fascists in the hills.
So, in short, I'm glad I read it. It illuminated a great deal for me about the situation in Spain, and prompted me to look up how the war subsequently developed (answer: not well).