All I know about AmEx is that a lot of shops don't take them and every now and then OzBargain features some great deals with the use of AmEx credit card.
Can someone please convince me why I would use AmEx instead of other bank credit cards?
PS why is it not available in so many shops?
Benefits differ from card to card, but generally, AmEx has more points/benefits per spending. Many shops don't take them because AmEx gets a bigger cut of each purchase you use with their compared compared to Visa and Mastercard.