(I also posted this over at the dpreview Micro Four Thirds Talk forum, so I apologize if your read it twice
I've had my E-P1 for two years now. Initially, I was only recording JPEGs, but as soon as I tried RAW conversion in Lightroom, I was hooked. Lately, though, I rarely ever process my E-P1's ORF, since the JPEGs are so good most of the time.
I use custom settings with "Natural" colour, sharpness -1, low noise reduction and contrast +1, and this yields very punchy but natural looking results. I even set my highest auto ISO setting to 2000, since I found the E-P1's JPEG engine to deliver pleasing results (suited for small prints) even at that setting. Paired with the 20/1.7 pancake, the E-P1 is my ultimate low light tool.
After shooting a late evening family gathering in dimly lit surroundings recently, I had to load the ORFs into Lightroom since I forgot to set a custom white balance, and also because I didn't bother with exposure correction. When I open the "Develop" dialog on the first picture and started manipulating the settings in the "Details" section, I was positively shocked. I had to dial in only very little noise reduction (luminance: 20, detail: 80; colour: 20, detail: 20) to get rid of most of the noise, and after tweaking the white balance and tone curves, I got very pleasing looking images that didn't appear to have been taken at such a high ISO setting.
Granted, viewed at 100% you can see slight colour blotches here and there - especially in the darker ares - as well as remaining luminance noise. But the former is really very subtle and hardly observable at display viewing sizes, and the latter is reminiscent of film grain, and in that light I would've use at least a 1600 ISO film, if not a 3200 (or a pushed 400 ISO film).
Here's an example, a picture I'm especially fond of since I find it turned out very nicely (partly due to the subject).
There is enough detail preserved, and I'm also quite satisfied with the colour rendition considering the circumstances. Yes, there is noise at 100%, but I find image quality to be /sufficient/ overall, and good for a 2000 ISO shot.
But the big proofing of the E-P1's high ISO capabilities has yet to come, when the pictures get printed in A3 size in a photo book. I am anxious to see how they hold up when printed this big. (I should probably print them in A4 at home first, to see if they need some more tweaking.)
So, essentially, what I wanted to say is that I am in now way reluctant to use my E-P1 at ISO settings as high as 2000. If the exposure and white balance are right, even the JPEGs will do for me, and when converting from RAW, the pictures demonstrate that the E-P1's sensor still delivers even when its output is amplified that much.
Will the E-P1 still be a good choice in 2012? Most definitely!