I bought this for my Lumix G7 after an overzealous drummer managed to destroy the internal condenser microphone.
$300 later and I'm not terribly impressed. The sound quality is poor, it constantly inserts loud bizarre electrical buzzing noises (think Megaman 3 Spark Level). Unfortunately, replacement parts for the Lumix G7 aren't really available yet, so I'm out of options for decent recordings. It is an attractive little device, though, and comes with a nice case, but it just doesn't work at all. It claims to be able to adjust its focus, and that seems to work, but still adds the buzzing noises.