The Samsung will accept a 1080p/24fps input, but it converts it internally to 1080p/60fps prior to display. And it will not accept a 1080p/24fps input from Samsung's own BD-P1200 Blu-ray player, a trait it shares with the Samsung LN-T5265F flat panel LCD.
It did accept a 1080p/24 input from the Pioneer Elite BDP-HD1 BD player, but its 24fps performance with that player was unsatisfactory. It skipped a frame or two every few minutes, which caused the image to stutter. I sent 1080p/60 to the set for all of my HD disc viewing.
Well the set is in the house. Did not have much time to do much beyond applying the menu settings listed here and at AVSForum.
Eyeballing it the geometry seems good but I'll reserve judgement until I can run some test patterns. No prism/halo issues. Using the HDMI connection with my HD-A1.
Black levels seem good as quick runs through Batman Begins scenes seemed fine. My God - scanning through The Corpse Bride was awesome in its 3Dishness! Upconversion on Return of the King was excellent as well.
Spent some time with my newly received 5689 last night. It is build 1016. Geometry is excellent and no halos are present. I do find the black level acceptable but not great. I have improved it by closing the aperture and putting the SB setting at 175.
Control of the iris is under the DB Aperture option on the service menu. The SB setting controls the black level in a range between 0 - 255. Getting into the 200+ range really darkens things up. If you need exact instructions - scan the AVS forum threads.