Sure, here's a partial list (in no particular order) and why I find them helpful:...What I will say is that beyond the 12 FPS, the rest of the features are "nice-to-haves", but not really "essentials", at least for most people. For low light wildlife work and sports, I'm making full use of all of the extra features...
could you elaborate on that for me? I am constantly trying to figure out what features are those nice to haves and trying to determine if they are worth the extra cost....
1. The build quality - Definitely tougher than the 5DIII, but the 5DIII is plenty tough short of combat
2. Viewfinder shutter - definitely easier and more convenient than using the rubber eye cover, or what I use, a hat.
3. Manual with exposure compensation - this ROCKS for sports and wildlife shooting when you're faced with changing light conditions or light and dark subjects (e.g. swans and crows), but it's easy enough to work around
4. Automatic Extender compensation - again, convenient (I often forget), but nothing a quick turn of the wheel can't do
5. AF-pt. linked spot metering. Great for sports and wildlife (similar to 3 above), in fast-paced shooting, but again, not critical
6. Multi-spot metering - convenient, but can easily be done in your head/on your phone in the situations where it's most useful
7. Face detect / color tracking AF - very handy with the 85L II at f/1.2 and gives better AI-Servo performance, but doesn't blow away the 5DIII
8. Higher voltage battery for faster AF with USM lenses. Noticeable, but not critical in most situations
9. Built-in portrait grip - it's "free" but then again, it makes the camera a lot bigger
10. X-Sync speed of 1/250s - helpful for a bit more freedom when trying to overpower the sun, but 1/200s isn't that much slower
11. Auto ISO upper limit above 1/200s (essential for sports if you use Auto ISO) - I sure hope Canon gives us this in a future 5DIII upgrade if nothing else. It cripples/crippled the Auto ISO feature and made/makes Canon look like idiots compared to Canon. Why Canon, why?
12. Better high ISO captures over ISO 3200. This one is really nice if you shoot at ISO 6400+ much, though the 6D has lower noise from what I hear.