I am now a silver elite member (or something like that) but will probably go back to the standard blue card because I haven't flown with them for a while now and you have to keep flying (I think 25000 miles in a year) to retain your status. So if I fly 50000 I'll get upgraded to gold. But the main disadvantage is you have to pay the taxes on any free flights, plus sometimes a fee if you don't have enough miles to top it up and you can only do this over the phone, so you don't get the reduced internet miles rate. So with Air Asia it's probably cheaper to fly with them. Also miles expire after 3 years but you can renew them, this reduces them though. I've flown to Australia and back 3 times but still don't have quite enough to fly to Perth free of charge, although I can go to Singapore return or Perth one way which is okay but then there's taxes and I have to pay for a return lag. So not as good as it looks.
Krisflyer - Advantages: Prestige- very hard to qualify, Few programs of similar stature in Southeast Asia - Disadvantages: Over-priced, Senior management does not respond to complaints efficiently at all, Too many higher tier members, difficult to personalise service