No catch... As mentioned the registration interface is shit and if you have multiple domains you cannot manage them or update them in groups, they must be done individually. I have bought ~30 domains there in the past few weeks and all went ok... Dont expect a godaddy or namecheap service though... but hey... transfer them down the track.
True, cheap is not synonym of "catch", just a marketing strategy as Yahoo, Netfirms, Aplus.Net, GoDaddy and other big registrars do. You get your domain at a lower price and you renew at regular registration fees. By the way, exabytes.com.my is offering domain names at 0.99 rm, which I have no idea how much it is but must be cheap. I don't live in Malaysia for give you currency exchange, but I have a site hosted there paid for a full year as blogging prize