The only way I use the term in a non-ironic fashion is to describe a special kind of synthesizer-and-nature-noises "music" that does wonders for insomnia.
Though Manheim Steamroller is okay, at least at Christmas.
There was good New Age music in the early to mid 70s. Island-period Jade Warrior, a lot of unknown, painfully valuable private press new age artists, Miken Oldfield, etc. (and that's ignoring the amazing European Kosmiche stuff like Ash Ra Tempel and Harmonia that gets lumped in with Krautrock but isn't really the same) It was originally kind of a weird offshoot of psychedelic music and a lot of it is very dark and weird. It didn't get really shitty until the 90s. Even some early Ray Lynch stuff is decent (certainly better than the new Animal Collective songs that basically rip his sound off and add beats).