The four hundred and twenty-fifth album: #425 Brian Eno - Ambient 1: Music for Airports
Sure, there's a lot of value in ambient music, and there are times where I enjoy having something to break the silence (although even then it tends to be something that is a bit more active). As a piece of music to focus on, however, an album like this falls flat as you can't get the feeling of falling into the middle of it, wandering in as it's playing. The start and end point become deliberate, removing the easier flow into the music.
Even then, the slightly discordant sound, created often with musicians somewhat separated from each other, becomes off putting and difficult to manage. It never quite becomes comfortable, which makes the music off putting in its own right. It might occasionally work, but there's never a point where the music really connects.