Received mine few days back too.
Some early findings:
1. Camera is much easier to hold with the improved grip
2. Lovely selfie LCD screen. (When in selfie mode, screen is not blocked by the hotshoe which I experienced in Olympus EPL5)
3. Nice individual dials for exposure, mode, aperture/shutter and the usual rotary dial for viewing photos (4 dials in all). The play and record button are small and I think could be an issue for people with big thumbs.
4. Loved the pop up flash which could double as a bounce flash if needed (probably useful in tight space like inside car or rooms)
5. EVF is very responsive, clear and feels natural (fast motion response). The eye cup can cover the eyes fully and really black out. (should be especially for those into Macro)
6. A larger capacity battery is used (i.e. the batteries are not interchangable between the M's)
7. Neck sling catch is now back to the usual design which means most 3rd party straps can be used (M2 used a special design)
8. The AF does not "feel" as fast as it claims to be when compared to M2. I used the word "Feel" as during actual run, it does manage to focus on fast moving targets with a higher keep rate than M2 on preliminary testing. My fast moving target here is running kids in the room under usual fluorescent lighting. I suspect it's the way the M3 shows up the lock on the screen. The focus box is now small with thinner lines. One thing I must point out is that there is no more focus box when using touch shutter (M2 has it). When taking photo using touch shutter, I pressed on the place I wanna focus and M3 focus and takes a picture when a lock is achieved. But it does not show where have I pressed on the screen. This is abit counter intuitive and weird so I hope canon rectify this in the next firmware.
9. The display of menu item is now cluttering the screen which gives an impression of a small screen. Unlike M2 which allows me to just show the important stuff like F No., exposure and mode, the M3 will show information like shooting mode, WB, Touch shutter and etc on the left side of the screen. This takes up a good 5% of the screen and I really hope they will add some flexibility in the placement.
10. In terms of operation, M3 feels smooth. But it was noted that M3 took a while to write the files into the memory card. This should be attribute to the huge data file size from its 24MP sensor. In view that I am using Sandisk extreme (45mb/s), I would not have expect this to be an issue. The main niggle is that I could not switch from previewing photo to shooting mode quickly like I could on the M2. I would expect Canon to solve this quickly as this is really puts a damper to the joy of using the camera. On a side note, I was able to improve the response by switching off all the bells and whistles available under the preview mode but I would expect it to be better. A 0.5sec delay will result in missed shots.
10. In terms of image quality, the first impression is that the details, dynamic range, sharpness and resolution have increased significantly but there is noticeable increase in noise as well.
11. There seems to be a digital stabliser built in but have yet to try that out.
12. Lastly, I would add that the menu has been redesign and takes some time to get use to. It is not the usual Canon menu which is simple and fast and does feel like the designer is not someone who shoots with the camera (key function are mixed up with other less used functions). Shall try it out further to see if this is a bumper.
All in all, I am really still sitting on the fences weather to keep M2 or M3. The M3 is significantly larger and offer better image quality and focusing. But I think the firmware needs further improvement to improve the camera handling. The M2 in comparison is really small and pocketable (esp with the pancake lens) and offers most of M3's capability. The key draw here is really the rotating screen which allows selfie, bounce flash and more manual dials.
How is the blackout time in single shot mode? EOS-M had a long blackout time after every shot, very irritating.
This was solved in M2 already and I am glad to report that M3 does not have the same issue except that the write time is longer. I would expect a fast memory card is needed to resolve this.