On the surface, the idea of Pink Floyd doing a sidelong instrumental composition for rock band with orchestra and choir sounds like a disaster. Even beyond the obvious question of how the hell you do an instrumental work and get a choir on it, the late '60s and early '70s are littered with such "experiments", from the obvious Moody Blues thing to Yes and even Deep Purple, and they're nearly all total disasters. Even Zappa's attempt at doing a rock and orchestal "hybrid" with _200 Motels_ was not one of his more successful ventures (though to be fair, as a talented composer he realized the inherent difficulties in getting an unamplified orchestra to play nicely with a loud rock band and mostly kept those two sides of his work separate). When you realize Pink Floyd is a rock group who are neither hugely gifted composers (as opposed to songwriting, which they could do very well) or particularly talented musicians, especially as regards the rhythm section, the difficulties increase. However, Pink Floyd did one thing right here that has ensured that Atom Heart Mother has to this day an excellent reputation among counterculture malcontents: They put a cow on the cover.
OK, no, that wasn't the only thing they did right or even the most important thing they did right, but it was an extremely good idea and worked out very well for them. But no, the actual best move they made was getting Ron Geesin to do the orchestrations. This was an excellent idea because Ron Geesin, better than most orchestrators, had a keen understanding of the absurd, and there are few things more absurd than a rock band trying to do a long-form orchestral work. (If you ever find yourself in a dour, humorless mood, consider this: Due to the technology of the times, Waters and Mason had to play the rhythm track for Atom Heart Mother in one continuous take. The prospect of this never fails to crack me up every time I think of it.) So instead of a long, turgid steaming chunk of Serious Music, Geesin's work reveals a number in which the choir chants names of breakfast foods, in which Geesin's own voice pops up during a particularly bizarre interlude to inform the listener: "THIS IS A LOUD ANNOUNCEMENT." This affinity for the offbeat, for the outright goofy, strongly informed Floyd's aesthetic at the time as well, but at the same time Geesin's considerable talents ensured that Atom Heart Mother wasn't just a 24-minute joke; the arrangements, while not the best thing ever recorded by an orchestra, are solid. Special attention should also be given to Gilmour's guitar solo on the track, which is to my ears the first truly great guitar solo he put on record. Very few orchestra/rock band crossover records, and certainly none from this particular school, achieve such a high level of proficiency.
The second side of the record is admittedly not so compelling: three shorter pop songs by Waters, Wright, and Gilmour respectively; Fat Old Sun is a decent enough Kinks ripoff and would become a wonderful song live, but the other two aren't among their best songs, and Alan's Psychedelic Breakfast, which frankly I think is very underrated and I'm not sure why everybody likes to rag on it, particularly part three, "Morning Glory", which is one of Floyd's most underrated pastoral numbers. Still, side two is unquestionably the weaker side.