I just did a trip visiting KL and passed through the terminal.OK you don't arrive in a big airport but it does the job.
There were no queues for immigration (entering and leaving)
Slight hassle getting the bus over to main airport.This is no worse than going from Terminal Three at Heathrow to Terminal One.The green buses run a regular shuttle every twenty minutes.
I turned down the Air Asia Shuttle into KL Sentral as they said it would take 1 hour 20 minutes and was jam packed.It was an old bone shaker with no bog.
Taxis offered to do the trip direct to my hotel for 56 Rgt - about 600 Baht and it took one hour door to door.