The Planets strongest suit is their very articulate, transparent, open and grain free mid-band. This allows them to make the most of acoustic recordings. They reveal plenty of detail and instruments are presented with their harmonic richness intact.
Voices in particular are rendered thruthfully, revealing considerable emotional cues and meaning.
If you are interested in trying out a pair of omnis I cannot think of a more cost effective starting point. The Duevel Planets are a great pair of speakers and whilst it is early to be saying this I will be surprised if I hear a better value component in 2007.