Corruption can be considered better then its predecessor overall because of the new gameplay, but it fails to become the ultimative Metroid of the trilogy because of the disappointing Sondtrack (better then Echoes, but still way inferior to Prime) and its lentgh: it's too short and it's a shame.
Secondly, it's way too focused to action in comparison to Metroid Prime, that was way more an adventure game, with it's center of mass around exploration and not shooting.
Third, it's too linear. And it's disturbing somehow, because the research of items and new places has been relativity put into a corner. For example, the ice side of Bryyo could have been developed more deeply widely then the 100x100 meters isle it is.
Fourth, I don't like the presence of other characters, of the federation and the fact that Samus works for the federation. Metroid means desolation, desperation, and a sensation of isolation. Samus versus everyone. Only her, and evil. THIS is Metroid for me.
So, it's still a great game, but Metroid Prime is better.