Like a previous reviewer here, I too noticed a brief flicker, particularly when the scene changes from a bright scene to a dark scene. This can be fixed, but in theory you need to get Samsung to send one of their agent engineers out - the guy had to wring HQ - but to save time tell them they need to switch off the Dynamic Dimming. This is done by accessing the service menu, switching Debug Mode to On, and switching Dynamic Dimming to Off. They won't tell you how to access the service menu yourself - its done by 4 key presses...you may be able to find out via a forum... ;-)
Alternatively, switching the mode to Movie setting is a work-around, but depends if you're happy watching everything on a very dark setting.
Aside from that, its a very good unit. I much prefer the flat-bottom design compared to the R72/R74 model.
And amazon delivered bang on time as usual, so full marks to them...!