I got what I thought was for me a decent return on my EP1 and "upgraded" to the EP2. My main reason was the EVF - I love the Lensbaby Composer - and figured it would help with the manual focusing.
(1) While I love the look and feel of the black finish, I do sort of miss the retro look of the original silver/chrome, but not much.
(2) The AF seems slightly improved (possibly wishful thinking). Seems like there is not as much hunting. Tried the 14-42 kit, the Pana 20mm and two 4/3 lenses - the 40-150 (new version) and the 14-54 MKII. I do wish that Oly did allow to make the Single AF points smaller - still too large.
(3) The EVF is fantastic! I can really see using it for manual focusing and not actually needing to have the Manual Assist Magnification on. It is very bright and certainly looks larger than any of the Oly 4/3 OVFs that I have used (though never had the E3 - largest is on the E30). Quibles: you must push the button on the EVF if you wish to view images on the larger screen - yes you can view them in the EVF, but I prefer the screen. There should be a firmware update to allow for this. Also the exposure of the EVF and the White Balance don't seem to be exactly the same as the LCD - not off by much but definitely noticable. However, the resulting images look identical.
(4) There seems to be some improvement in the flash exposure. I have the FL36R and the FL20 and on both of them with my EP1 I was generally having to play with the flash exposure settings - generally slightly over exposed.
(5) Looked quickly at the two new Art Filters - will reserve judgement but so far they will not get nearly as much use as the Grainy B&W does. What I don't understand is why - if you are using the Super Info Menu is there no way of changing Art Filter without rotating the Mode Dial - should be on the menu like it is on the Live Menu.
(6) CAF Tracking - very interesting. Played with it a bit, but on something that was not moving. Lots of fun watching the little green square move around while tracking. What's nice is that it also works in Video Mode, but have not really tried it out yet.
That's it for now. If anyone has any questions, feel free to ask. Will try to post some initial shots over the weekend.