I got this TV on a swap with Sony on the 21st of April, so far it has been AWESOME! (Sony took back my defective 820 and gave me a 850) 46' model. I will be comparing the HX850 to the HX820.
Pros:
*Slimmest bezel of any Sony TV yet
*Silver lining around the bezel adds a nice touch
*Input lag seems better on the 2012 850
*Less adjustment needed right out of the box, at least in my case.
*Speakers seem a tad bit better this year, but nothing to brag about.
Cons:
*Remote is garbage, Sony needs to bring back the remote they used with the HX820. A victim of cost-cutting.
*Illuminated Sony Logo is gone. Another nice feature butchered by Sony's new cost-cutting strategies of 2012.
So-So's:
*3D viewing seems to have improved overall over the 2011 HX820, however tilting your head at all will ruin the picture. Perhaps this is resolved with the new 3D glasses? I am using the TDG-BR250 glasses.
*Motion sensor is gone. Never really liked this feature, but it was a good idea.
Overall the HX850 is a superior TV to the HX820, which is saying a lot considering the HX820 was and is an amazing set. Black levels are similar to the hx820 (awesome) and picture quality has gone up. As always, Sony is king when it comes to displaying the correct colors, vibrant and colorful to say the least.
Good set!