When I scroll items using the j/k or shift-j/shift-k keyboard shortcuts, I find that the next item is moved all of a sudden to the top to become the first one in the list. I find this bit distracting. In Google Reader, the item used to stay where it was and simple keep moving downwards.

It's hard to explain the actual behaviour, but the difference is immediately recognizable if one were to scroll using keyboard in both The Old Reader and Google Reader