I have not much problem with Air Asia so far. I can only think of the 2 delays I had early last year. One was on a flight from KL to Bangkok and the other was from Phuket to KL.
After reading what fountainhall went through with Thai Air Asia flight to Chiang Mai, I might have to book a flight to come back from Bangkok instead of going up north on my next trip. My itinerary is KL to BKK to Chiangmai to KL. Might as well give Chiang Mai a miss as there isn't much to do there. Only problem is cheapest fare is FD flt to KL at bht1809 bht...other flights are bht2809. After getting used to the FOC tickets, these fares seem exhorbitant!!