I bought 'On Land' this afternoon and have been playing it constantly -- it's been round about six or seven times already. The first time, it sounded utterly familiar, like music I'd heard a long time ago and forgotten. Every time since, it sounds different and new. I already had 'Music for Airports' and 'Plateaux of Mirror' (with Harold Budd), but 'On Land' has convinced me that Eno is, without exaggeration or qualification, a great artist. Even his liner notes are intelligent without being pretentious, a rare achievement for a musician!
Although very superficially similar, it doesn't take long to realize that Eno's ambient works are a world away from the lazy, sonically unadventurous tinklings of countless 'New Age' pieces (many of which were probably inspired by Eno, unfortunately). In 'On Land' every sound is meticulously placed, every treatment thoughtful and, needless to say, beautifully produced. Moving away from the idea of 'performable' music towards pure studio recordings allows a degree of control -- crucially, control of tonal contour and spatial organisation -- that makes these tracks more like aural sculptures than music. That's probably why they sound so different on different systems, in different rooms, at different angles from the sound source etc.
If that makes it sound like an academic exercise, be aware that this is also a very emotional record -- although the emotions communicated are usually obscure, ineffable, almost impalpable. Whereas some of Eno's other ambient works are explicitly NOT to be listened to directly, I can't help feeling that 'On Land' demands more focused attention. It will certainly repay; after just a few hours, it already feels like one of my favourite records.