Summary: I got this to fit onto my Olympus Pen EPL1. I have Zuiko 14-42mm lens that came with the camera and after reading the description of the Fisheye didn't envisage any problems. However when I received the Fisheye lens I couldn't get it to fit. After a bit of head scratching I realised that although my lens seemed to be compatible, it wasn't. The FCON-P01 Fisheye only fits on the 'II' variant of the lens (which I guess is the second version).
Summary: This is a very well made adapter and the slightly high price tag is justified in terms of quality of glass and build. However, this actually weighs a fair bit more than the 14-42mm lens it goes on and when extended (meaning not locked) it feels like it's putting a fair bit of strain on the lens. On the plus side, the adapter does produce some very fun and creative fish eye pictures and is a very cheap alternative compared to the Panasonic 8mm fisheye lens.