I forgot to mention short battery life as an issue - I keep a charged spare in my briefbag when I'm carrying the DP2. I have not seen the green corners or the magenta grid. The camera will use a fast class 10 card, which speeds RAW writes. My computer won't regognize these cards, though, so I have to download using the cable.
I have compared shots with my Panasonic LX3 and the IQ of the Sigma blows the LX3 out of the water. However the Panasonic is more of an all-around compact (even with its wide lens and limited zoom) and has hella better low-light performance due to the faster lens and OIS.
That said, here is a 37x crop of a jpg made with the DP2 (ISO400, 1/60s, f3.2):
I am planning to compare the DP2 to the R-D1 with the 35mm Summilux ASPH on it - that seems like a fair comp to me.