This update of the phenomenally popular Pokemon series for the Gameboy Advance definitely is based on the "if it ain't broke, don't fix it" principal.
Very little of the underlying gameplay has been changed or improved, but with the addition of new modes such as 'Contest Mode' (a kind of Pokemon Crufts) there are new things to see.
If you can stomach the cuteness of Pikachu and chums, you will find an engrossing RPG classic here that is well worth your time.