I just took my new 5DmkII for its first shoot. Since I've been using a XTi for the past 2 1/2 years, I had problems with the mkII:
I couldn't get quickly to the controls I needed, which button/knob do I press, I NEVER looked at the LCD on top of the body, I had trouble using the spot metering, why are there more than one photo shown on the rear LCD, top wheel or back wheel. And this even AFTER I read the manual.
I'll always give "beginners" a break since I've gone through the same things they are going through.
Now, as for the truly stupid, that's another story
Too much stuff, not enough shooting time.
Canon T4i (2 lenses), Fuji X100s, Olympus OM-D EM-1 (3 lenses)