I just finished (and S ranked) DR2: Case Zero.  Really enjoyed the experience.  It has got me very pumped for Dead Rising 2.  It was a little disappointing not knowing what happened to our good buddy Frank West, but hopefully the full game will disclose that coveted information.  The AI seems to have gotten better so the escort missions don't seem to be as big of a pain in the ass now.  That is very much appreciated.  I hope the weapon combinations continue to impress overall in the full experience and they make them even more useful.  It was also a breath of fresh air to be able to move and shoot at the same time.  Overall, it has got me impatiently waiting for September 28th.