What happens if you input the signal at 60Hz? Does that improve the picture? In some cases, this may result in satisfaction. I would suggest trying that first.
I'm not sure if it's somthing you should "expect" per se, but it may be due in part to the processing and upconverting of the picture. There is a picture setting forum at CNet that may help you get your settings to where they want to be. I'd recommend trying that as well.
I purchased a Samsung LN37B650 from Best Buy about 5 days ago. I've tested the TV using 3 different sources: PS3 playing a Blade Runner Blue Ray set to 1080/24hz mode, a standard DVD player hooked up HDMI in both 1080p&1080i mode and an HD cable box. In all instances the picture looked sped up and artificial. Disabling the Auto-motion Plus setting made a big difference but it certainly hasn't eliminated the problem. Basically it went from looking like a super high quality security camera to a BBC soap opera. There are certain scenes where the effects are less noticeable but 90% of the time it looks absolutely comical. I found this surprising after reading this sites review of this very unit. I even duplicated the settings you linked to in the review. Nothing seems to work. So, here are my questions:
1) Is there a setting located somewhere besides the "picture settings" or "advanced settings" that could remedy this? I know it's not likely but worth a shot at least.
2) Is this something I should expect from all 120hz LCD's in the 1k-1.15k range? Is there a particular model that is especially known for not having this issue?
3) Does this Samsung perform a 2:3 pulldown or a 5:5:5 pulldown? Could this be where the problem lies? Could it be fixed in a firmware update?
Let me state once again that disabling the Auto-Motion plus didn't solve the problem but only made it less severe. If you can think of anything that can remedy this issue please let me know. Anything you could offer would be greatly appreciated. Thanks so much!!