A very fair and even-handed view of the situation. Sometimes utmost perfect IQ just isn't the core element that sells a product. Everyone complained about the AF on the 5D and 5D2, but both had great IQ? The 5D3 came out and fixed the issue. Now that we have a camera with great AF that is within spitting distance of the 5D2, some cry about the IQ. There is always something to complain about.
Probably because people expected that in 3 years between the 5D2 and 5D3, there would be some more improvements in the IQ. The 5D3 is still a very good camera, it just had a few little quirks and letdowns that kept it from being a perfect camera.
1. IQ wasn't much improved
2. Those black AF points are impossible to see when shooting a dark reception.
3. The SD card slot was crippled to 20MB/s
4. When shooting to both cards, the write speed is super slow and the buffer is pretty poor.
1. Two card slots
2. The new AF is really good
3. 6fps is enough for a lot of sports and makes it a really good all-around camera.
4. New Q button menu is great and super handy
5. New menu system was vastly improved and much easier to navigate
6. So many cross-type AFs
7. Silent shutter is great
If the SD card slot actually worked as well as expected and the sensor was more of an upgrade, it would have been just an incredible camera. As it was, it is still a really good camera, but a few oversights (?) by Canon makes you wonder as to why they didn't really get the grand slam there. It isn't like a fast SD reader would have been that hard to implement.