I have owned a pair of these for some months. They are quite plump and well filled and comfortable in use. Like all such products, they need regular shaking and plumping as they would otherwise be rather flat and hard.
They have only now started to shed the odd feather, just one or two a month, and if they can maintain that rate of loss of filling I will be very happy.
UPDATED @ 4-2012
Other than the few previously mentioned, I don't think that another feather has since escaped. The covering therefore appears to be very effective. However, after using these pillows for approaching 18 months, even after plumping, rearranging and whatever else is needed at least once every night, any resemblance to their original shape and structure is purely coincidental. Even after 30 minutes, they often roll edge to edge along their length to form something similar to a bolster. That is very uncomfortable!
Although quite well-filled, the overall experience has not been exceptional. A good pillow should last for 3-5 years before needing to be replaced. If they are only good for about a year or perhaps less, it makes them rather poor value for money and, if I had that information at the time, I would not now buy them. Not over-pricey for a feather pillow, there just has to be better without needing to pay a fortune!
I am now actively looking for their replacements!