I really dislike Fusion's health economy, Samus is also made of paper in that game which makes it artificially harder than other games in the series. It has some of the most annoying upgrade placements, The SAX sequences are just annoying instead of scary, and I hate how most of the bosses have shrill screams.

Fusion also started the gradual shift away from exploration, tension and atmosphere in favor of action. Which is why I rarely go back to any of the post super entries sans prime 1 and 2.