There is quite a leap from the 3rd to 4th. Biggest was the fact there is an app store on the 4th where as the 3rd you just got some for the region you are in. The apple TV will know you are in Hong Kong inless you change the dna settings. If you sign in with your UK itunes then you will get UK stuff but NO bbc iplayer.
Get used to the 3rd grn but you will notice a huge difference with the 4th, especially if you like watching live TV.