Richard Butler, reviewing for DPReview:
Beyond the physical distinction, there’s almost nothing to set the two models apart. The E-P2 offers two additional Art Filters (the mock tilt-shift ‘diorama’ mode and ‘cross-process’) and gains a menu option to adjust the brightness of the EVF but that’s it. You can almost think of this as an E-P1.1 that needed a more marketable name.
Interesting commentary were also made during the time of the announcement:
The launch of the E-P2 so soon after E-P1 might prompt the more cynically inclined to wonder whether this is the product Olympus originally planned to create – though its similarity should mean early adopters of the E-P1 don’t feel stung for having exercised their credit cards so readily.
This is the kind of thing that I disagree about the imaging industry, they try to follow the computer industry, where product cycles and features drive the invention, but not real needs & solutions. You can read my long thoughts on the “Blurry Picture” piece I wrote a while ago.
update: Here’s a reason for not to upgrade from E-P1
Read the Quick View