"Musical" means "Hey, I like this one so much, I can't be bothered with trying to explain why." It's a pretty recent descriptor of choice, along the lines of "sounds more like music, less like hifi." Whatever. By itself, it doesn't convey any more information than making contented grunting noises does. To be more charitable, it conveys the sense of "getting it right," even though the piece might not be the ultimate in one or more specific audiophile qualities. The problem is, "getting it right" totally depends on your personal preferences. It's often hard enough to interpret people's usage of terms like "forward," "warm," "compressed"... The word "musical" is pretty much off the charts in terms of subjectivity.
That said, I liked Noble's answer, too.
That said, I liked Noble's answer, too.