I have a E-PM2 and a G3 (same sensor as GX1). I bought the Olympus as a second body for the small size and the wireless flash-options, which are great. As I had a E-PL2 for some time, I could easily adopt to the Olympus-menues. I will need a VF2 for x-mas, the LCD is hard to see in sunlight and with the weird 16:9 screen the 4:3 pic is pretty small (looks like 2006). The IBIS is hit and miss, sometimes it works wonder (low SS), sometimes it makes things worse (SS above 1/30). I tend to leave it OFF and only use it for SS below 1/30, where it really shines. Both bodies AF very fast, but when lightlevels drop the AF becomes slower on the Olympus and more unreliable than the G3. There should be an advantage to IQ in the E-PM2-pics, but in real life use it is hard to see a difference (I don´t pixel-peep, I´m sure you can detect the improvements when doing so).
All in all I really like the E-PM2, but if it wouldn´t do the wireless flash, I would have bought the GX1.
As always,your mileage might be completely different .....