Product review (2 stars): I cannot recommend Samsung after this
We had a service call and the technician told us the oven was working properly even though we had measured wide temperature swings.  He said they all do that.  Not really a good reason for an oven to not hold its set temperature well.  I will admit our thermometer was partly to blame for me thinking the readings were further off than they were but the oven does not behave "normally" in that it says it is pre-heated but isn't (the technician also said they all say they are ready before they reach the set temperature) and when you open it to put something in or take something out the temperature will drop a lot and takes a while to recover.