Go here for FR/LG's new features: http://dynamic3.gamespy.com/~psypoke/lgfr/index.php
Basically Sapphire and Leaf Green have different storylines altogether, with some differences in features. No one said Leaf Green was or wasn't better than Sapphire, because Leaf Green is a remake of Green while Sapphire featured a brand new region (ie Hoenn) altogther. The purpose of Leaf Green is to complement
Sapphire, and not to compete with Sapphire. This is because Leaf Green will allow you to get RBY/GSC Pokemon into Sapphire, whereas Sapphire had very few "old" Pokemon, namely the Raichu family, the Tentacool family, the Kingdra family, and so on.
Hope this answers your question(s).