I had ordered the D54250WYK unit and everything was working perfectly ok, except the IR. When on XBMC I would move down in the remote, the remote would move one or two lines when constantly pressed down and stop. Lots of key presses were being missed. I then replaced it with an external IR of Lenovo and that would work perfectly fine.
I went ahead and purchased another one from FRY'S and the new unit works perfectly smooth.
Earlier I had the previous edition of the NUC and the first unit had networking speed issues. That too had to be replaced after days of debugging. This gets me to think that the NUC is plagued with Quality build issues.