A huge bummer as I bought 5 of these cards, which are now all but useless to me. I am using a Panasonic GH-2, and the card stops recording at anything above 50Mbps... I bought this hoping it will be an upgrade from the Transcend cards which happily record at 140+Mbps....
Sustained write is horrible, the recording stops after 5 seconds. On the lower bit rates, the clips do not span, so when the 4GB limit is reached the recording just stops.
The shipping was very fast and packaging was great but the product is unfortunately very sub-par.
If you need cards for high bitrate recording, steer clear of this.