Bottom Line For Me
For the price I paid, I'm keeping them - but they definitely are not a substitute for the Bose headphones.
Vendor and Product Info Links
I bought two sets in November 2007 from Buy.com at 69.99 with free shipping - no one could touch that price at the time.
My Relevant Product Background
I'm not a super-dooper audiophile - just looking for some good headphones that deliver. Don't even really need the noise cancelling. I am replacing a sub-$100 pair of Sony corded headphones for piano practice and movie watching.
What I Like
The C820s are light on the head and on the ears. They don't squeeze to hard and they fit my relatively large ears and head comfortably. Every possible connector is included for air flight, angle connector and a large jack adapter.
The wire connecting the headphones is jacked on the headphone end - so if the wire fails, you can replace just the wire.
It only takes one AAA battery - reducing the weight and battery requirements.
What I Don't Like
Many web shops are positioning these as an alternative to the Bose noise cancelling headphones - I am not sure they deserve quite those accolades.
Size, Shape, Construction, Available Cases (Form Factor)
The cord that ships with the headphones is very light duty. I wasn't expecting a full fledged curly cord - but this is lighter than some in ear headphones. Since it has a jack on the headphone end, you'd think I could replace the cord with one of my liking - but alas, the jack fitting is narrow and deep - I am highly suspecious this is done on purpose so that you have to go back to Jabra for a replacement - it's just the snuggest, narrowist, most precious fit I've seen for an audio jack.
The protective case that ships is very sturdy. However, it also requires removal of the cord to close around the headphones. It is a stiff case, but with a zipper that unzips all the way (like a jacket or coat). It also requires that the ear cups be rotated flat. It seems like it would be difficult to store and handle on an airplane - but that's not my intended use. It would be nice if the case could be used to quickly stow the headphones (near the piano in my case) - but the case design assumes that you want to take the time to break the headphones down all the way and mess with zipping the case and then all the reverse stuff to use them (obviously worth the hassle if you are travelling).
These headphones can be run without the battery (or noise cancelling switched off) but they are notably quieter and much less bright. With noise cancelling on, if you are in a quiet environment, you hear hissing when there is no sound coming through the headphones. For something like piano practice where the main intent is simply to be quiet for others - this is a much more frequent situation than for other usages. They have decent frequency response for the price.
A Note to Jabra
It would be nice if the case were a little more usable for non-travel situations. Would definitely like to see the jack on the headphones be more compatible with other 1/8" jacks - especially since the included cord is so light duty.