The sheer number of characters running around should be one of its most outstanding features. Animation (character animation -- meaning quantity of characters, and quality -- higher animation-skeleton bone counts) is one of "those things" that the PS3 should really excel at via the SPUs.
I would imagine Insomniac may have intentionally tried to incorporate features in R2 (like high character counts, and really detailed animations) that showcase the PS3 over its HD rival, which shall remain unnamed such that we don't attract people not playing R2 to the thread. =)
I won't be able to pick R2 up for like two weeks. *sigh*







