The thing is the AF is just a little tricky and counter intuitive, i.e.
not user friendly, sure I'm not saying it isn't a great AF system for sports, it's just a little picky at details sometimes as the person I quoted below has found, and his comments seem fairly typical for someone who's honest and has used a 7D for a while.
In short it's a great AF system, it just needs a little refining.
I also think the softer IQ and higher noise levels of the 7D compared to other Canon 18mp crop sensors lower down the chain (550D 600D 60D) also gives the 7D a bad reputation at times, often 7D users even get upset when someone highlights this and squawk
that the 7D's sensor+filter isn't softer and just need more sharpening and noise reduction in PP...
'quote'