Summary: I have had this TV for 17 months and I like it except for two things. First, the flicker when watching 3D with the shutter glasses is so bad that I stopped watching 3D. Although the system runs at 120 Hz it is 60 Hz per eye, so, before you buy a TV with this type of 3D technology make sure you cannot see 60 Hz flicker (not everyone can). I recently saw a LG 3D TV with passive glasses and I did not see flicker.
Summary: I just bought this TV. I had Sony Bravia KDL 46EX700, the picture was amazing but only when sitting infront of it, so i left it go. Now, comparing this two tvs, despite the fact that they are different technologies, i mean LED and Plasma i most say: Picture quality for samsung seems to be poor next to Sony Bravia (slight lack of texture, darker look, poor or excesive picture edge handling ).
Cons: I had my parents by the 63" version of this tv and it died in 4 days. They had sound but no picture. A quick google showed this is a major problem with Samsung. http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=samsung+plasma+sound+no+pictu