It's a completely different cam and module. The new cam has bearings instead of bronze bushings and is smoother to draw and slightly faster. I'd also say it's quieter. Good luck with your new rocket!!!
I think that wwag summed that up nicely. The 2004 I-cam definitely has a nicer feel in my hands compared to last year's I-cam. It is actually quite similar in feel to the single cam found on last year's Patriot model.