Here's my current stream of consciousness thoughts.
Pocketability: for a man's dress or casual shirt, I don't find the Mk2 any more difficult to pocket than the original. The extra 1/10" of depth doesn't affect that at all, and the slight bump for the accessory shoe is even less consequential. If I were putting the camera in a tight jeans pocket, I might feel differently. I find that I do notice the extra ounce of weight, which surprises me, but it's not enough to afffect how I feel about shirt pocket carry. One other note: my recollection is that the Mk1 would fit into my shirt pocket with the Sony
ever-ready case on it (I might be mis-remembering, and I can't check now because it's sold). The Mk2 will definitely not fit into my shirt pocket with that case.
Image quality: I did some pretty extensive but informal comparisons while I had two Mk2 cameras and my Mk1 last weekend. I checked at ISOs from base ISO to 800 and at apertures from widest available to f/5.6 and at a variety of focal lengths from extreme wide to extreme tele. Based on that group of three cameras, with the raw files processed in LR5 with no processing other than applying the Adobe Standard profile, I see no observable difference in low-ISO sharpness. I did not check OOC jpgs at all, and I didn't attempt to process any of the raw files for best presentation.
I did not check high-ISO performance. I'm happy if the consistent view that the Mk2 offers between 1/2 and one stop better grim light performance. Frankly, the Mk1 was good enough that for me (and YMMV) the BSI sensor was not a big motivation for upgrading, although if (as Sony claims) low light AF is improved, that's very nice - almost more important than an extra stop of sensitivity and reasonable noise control.
Exposure: I found no observable, consistent difference between the Mk2 and the Mk1. In other words, the Mk2 raw files were not less exposed.
WB: I also did not observe any differences between the Mk2 and the Mk1. The subject was a wall of bookshelves in our living room with mixed halogen and daylight lighting.
Bells & whistles:
Accessory shoe: a month ago I thought this might be useful, but I don't shoot video and would never use anything other than the integrated flash (and then only in bounce mode, which you should try if you haven't, as long as the ceiling isn't too high)...an EVF would really destroy what is for me the most important attribute of the camera - pocketability - so the accessory shoe doesn't do anything for me, but also doesn't detract from the camera.
Tilt screen: I originally thought the tilt screen would not be very useful, but the ability to get high-angle shots, and to get low-angle shots without being on my knees or on my knees and elbows, is very attractive. I rate this a major plus and in my opinion possibly the single most persuasive (maybe the only) reason to chose the Mk2 over the Mk1.
WiFi/NFC: I don't have any NFC devices but if I did I am perfectly happy to manually connect on WiFi...I tried Sony's PlayMemories phone app for remote control and thought it was light on features and a little slow/unresponsive, so I don't see myself using that much but maybe some occasion will come up where that's useful...I didn't test file transfer speed over WiFi because the raw files from a 20.2mp sensor don't seem likely to transfer at an acceptably speedy rate (and I don't shoot jpgs). I will say that I found connecting the Mk2 to both my phone and my router were quite easy, even without reading the instructions, but other people seem to have different experiences.
New Menu Settings
I do like the ability to disable the movie button unless the mode dial is set to video a minor plus - no more accidental videos.
The step zoom doesn't seem particularly useful to me, other than for trying to do comparative shots as I was doing last weekend, but YMMV on that.
That just about exhausts my steam, I mean stream, of consciousness.