I know this thread hasn't been active for a while but I thought I would breathe some life into it ...
+1 for the M7. Bought mine used from a fellow RFF'er in 2011. It has the upgraded VF but the original optical DX reader. Never had any issues, and I've used the camera frequently since I bought it a year ago.
Quirks that I've noticed:
a. as presspass noted above, I don't like the 'power on' lag. IMHO that takes too long. Sometimes I feel like I'm going to miss a shot because I'm waiting for the damn ISO indicator to go away.
b. I have also experienced the wildly fluctuating metering issues mentioned by sepiareverb. The first time it happened to me, I became extremely concerned! I kept my calm, and started with the simple and obvious: let's try a fresh battery. Problem solved. That being said, the M7 seems to devour batteries faster than other cameras I own. Not a big deal, though. I just make sure I keep a spare in my camera bag.
c. the flashing dot in the VF is odd. It doesn't bother me, but I can see how it would drive other people a little bonkers. That being said, a film SLR with a vertical Christmas tree of LED's is much worse.
d. Interestingly, I can definitely notice a VF difference between the M7 and the .72x black M6 that I also own. The M7's viewfinder is superb. Clear and crisp in all kinds of lighting. I have had intermittent flaring with the M6 and THAT drives me bonkers! Extremely annoying when it happens. If I didn't love that M6 so much I'd probably sell it and just use the M7 all the time.
A final note: I think the M7 is a beautiful camera. It's a pleasure to use, and definitely has its own character. In fact, I think it's relatively under-appreciated in the pantheon of Leica M bodies.