I have that TV and I love it. It's great for using with a PC too. I found it smoothed some frames in Bioshock at 1920x1080 on my 8800 GTS 640MB.
I use the 120Hz but it depends on what I am watching. It looks good with some stuff like Blu-ray movies but depending on the source material it can artifact. Not for everyone though. My brother hates the 120Hz mode.
Originally Posted by Mr. Hunt
Trying to get my stuff in order to get the 52 inch from Samsung... the 650. I hear a lot of people complain about the 120hz, but I mostly want the option (haven't messed with it much in person, outside of seeing a "demo" in Best Buy), and I also want to be able to do 1080p/24hz.