Here are a few that come to mind...
-Delayed games
-Loss of exclusives
-Sony's laughable E3 2006 presentation
-Console sales not living up to expectations
-Exclusive sales not living up to expectations
-Lack of JRPGs
-Exclusives that flopped
-Timed 360 exclusives
-Mocking of Sony fanboys
-Price of PS3
-Negative media
-Inferior version of many multiplatform titles
-Unreal Engine 3 problems
-Sony's lack of direction
-Exclusives 360 DLC for some multiplatform titiles
-360 lead console for many multiplatform titles
-Failure of Sixaxis
-Sony arrogrance