Depending from where in the world you are travelling from, the flight to Korea will in all likelihood be long and arduous. Long haul flights get very tedious after a short time, especially if you are not flying first class.
Our Flight was around 20-23 hours long with two stop overs, departing from Cape Town, South Africa. If you find yourself in a similar situation, then its best to be prepared. Drink plenty of fluids, wear foot massaging socks, walk frequently and try and get some sleep.
We flew with Singapore air, and were very impressed with the service on board.
When you arrive at Incheon International Airport in Seoul, depending upon your time of arrival, the process time from embarkation to luggage pick up and exit can be quite a speedy process (Korean efficiency), but could take longer, especially if you arrive during the peak time of Korean New year (Chuseok). If this happens, please practice patience.